K.
I certainly can't claim this to be any sort of professional opinion [:)], but I wouldn't be worried. My daughter is 2.5 and did the exact same thing in the very recent past. She pulled her hair out (only on one side) when she was lying in bed either before or after sleeping, when bored or sleepy. She twirled the hair around her fingers and rolled it into little balls. It got to the point where she had really pulled almost all of it out on the one side, and that was disturbing, but I really didn't see that it was any sort of "problem" since it wasn't a stress-induced behavior. I never brought it up to any doctor, but she did stop on her own. We went to get a haircut (the first one) to kind of even things out and now we're back to normal again. As long as it's not something that is obviously stress-induced, I'd say your daughter is just learning about her nifty little body and will soon stop. Just keep reminding her patiently!