Small swollen lymph node under arm about 1-1.25 cm. very soft and moveable. no pain. no signs of infection?

Probably still OK: Watch it for a few weeks. If it gets bigger have it looked at. If it goes away then it was probably a healthy response to an undefined insult.

Monitoring Centers: Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells/digested food. Lymph nodes "taste" the lymph everywhere for bad stuff like bacteria/viruses/cancers, etc. When it detects a problem, it alerts the immune system and your body reacts. They enlarge in response to the inflammation they create when they react. They shrink when all is well.