It depends on the size & how long they have been there.
There are lymph nodes in your arm pits that can swell if you have an infection. Nodes may be swollen even if you do not feel any symptoms because your immune system is fighting the infection without you realizing it. Swollen nodes are usually tender. If hard/painless or are concerned see your dr because it could be something more serious.
Answer assisted by Nicole Bressler, Medical Student