I remember reading that in 1939 Andorra found out it was still at war with Germany from World War I since it had been forgotten at Versailles. A peace treaty was quickly concluded and Andorra remained neutral in World War II. Can anyone confirm this?

1939 Sep 25, Andorra and Germany finally signed an official treaty ending World War I. The 1919 Versailles Peace Treaty failed to include Andorra. https://en.wikipedia.org/wiki/List_of_wars_extended_by_diplomatic_irregularity

The tiny agean nation of Andorra declared war on Germany in 1914 along with many other nations. However, the Versailles Peace Treaty failed to include the nation, and it remained at war with Germany throughout the 1920's and 30's. The country's army composed of 10 people, however, and its military budget was 4 dollars per year for ceremonial blanks. The soldiers, however, wore pins reading "TOUCH ME IF YOU DARE", the country's national motto. In 1939, Andorra found itself involved in two world wars at once. A peace treaty was finally signed with Germany on September 25, 1939, during the invasion of Poland at the start of World War II. This document brought peace to the Andorrans for the first time in 44 years and officially ended the first world war

From memory I believe Berwick on Tweed remained at war until around 1970. My understanding was that the powers that were in 1914 were unable to decide whether the town was in England or Scotland and, in a hurry and to be on the safe side, they included it as a separate entity in the declaration of war. But it too, was forgotten about at the time of the Treaty of Versailles. It is, though, possible that this was a declaration of war against the Bolsheviks as I seem to remember that it was the London correspondent of Pravda who ceremoniously arranged for peace to come to the sorry citizens of Berwick.

I'm not all that sure about the Andorran peace treaty story. I've googled and only found it mentioned on "wacky story" sites. I couldn't turn up any reference to an actual treaty even though I had a specific date (25 September 1939) to work from. Since Andorra only became independently sovereign in 1993, it seems unlikely that it had actually declared war on Germany during World War I, though I suppose you never know. If there is any truth in this at all, one possible way in which it might have come about is because prior to 1993 reponsibility for Andorra's affairs alternated (annually I think) between French and Spanish authorities. It is possible that Andorra might have been administratively French when France went to war in 1914 and Spanish when the Treaty of Versailles was signed. Just a guess though. There's a lot of factual stuff about Andorra here:
https://www.britannica.com/place/Andorra

It is mentioned in webcom.com which has the following:

The tiny agean nation of Andorra declared war on Germany in 1914 along with many other nations. However, the Versailles Peace Treaty failed to include the nation, and it remained at war with Germany throughout the 1920's and 30's. The country's army composed of 10 people, however, and it's military budget was 4 dollars per year for ceremonial blanks. The soldiers, however, wore pins reading "TOUCH ME IF YOU DARE", the country's national motto. In 1939, Andorra found itself involved in two world wars at once. A peace treaty was finally signed with Germany on September 25, 1939, during the invasion of Poland at the start of WW2. This document brought peace to the Andorrans for the first time in 44 years and officially ended the first world war.

From webcom.com 2003 article, no longer online.

There are some reasons to be suspicious of the webcom reference. Andorra isn't an Agean country for example; it doesn't keep a nominal army of ten men, it has only police; and its motto is "Unity provides strength" not "Touch me if you dare."

I saw that one when I googled "Andorra motto", but it was the only site giving that answer. There were scores of hits, including old AFT faithfuls like wikipedia.org, nationmaster.com and 4reference.net, quoting the motto as:
Virtus Unita Fortior (Unity Provides Strength) which is why I tend to favour that answer, though I'm not sure what source would be definitive.

http://old.qi.com/talk/viewtopic.php?p=391853

In August 1914, with seemingly all of Europe caught up in the Great War, Andorra chose to declare war on Kaiser Wilhelm II's Imperial Germany. The Andorran military was composed of only ten part-time soldiers that assembled a few times a year for ceremonial reasons. With no effective expeditionary force to send to the far away frontlines, World War I passed relatively quietly for Andorra. So quietly that the country was not even invited to the Versailles Peace Treaty negotiations. The active army was replaced by the Servei de Policia dAndorra in 1931.

Since Andorra and Germany signed no peace, a defacto state of war existed between the two countries until September 25, 1939 (some sources incorrectly state 1958) when a reparation-free treaty was signed, finally ending World War I. The fact that World War II had started twenty four days before on September 1, 1939 has been largely lost on historians. Andorra, after living in a state of bloodless world war for twenty five years, decided to sit out World War II. With the fall of France in 1940 and the rise of the Vichy regime, Andorra again felt threatened. In 1942 when the Germans occupied southern France a German unit was sent to occupy the country but they were beat to the punch by Spanish Civil Guards. With the 1944 Allied invasion of southern France and the subsequent German withdrawal, Andorra interned trapped German troops. By an odd twist of fate Andorra fought Germany in World War I and never saw German troops, but was occupied by them in World War II, where it was obstensively neutral. The end of the war left Andorra free of foreign troops again and since then has remained so.