V.M.
THis happened to my daughter but she has other issues that may have caused it. I ended up Not taking her back to the dermatologist, although I did try calling to see if they would give me some advice over the phone, which they did not. She was around 3 at the time and is 5 now and it hasn't happened again. I didn't treat it other than to just keep an eye on it.
Gosh this makes me sound like such a bad mom, but the dr was 2 hrs a way and there were alot of other more important health concerns we were dealing with. I'm just trying to say, your daughter is probably fine, If seeing a Dr would reassure you, then do it. I would just be concerned if it happened multiple times, or if there was any redness, soreness infection etc. Good Luck.