Yeah, I just had this happen on my last batch. The little buggers were relentless this year, the worst I've ever seen them. I can't figure out how they got in there, but I had 8 or 10 of them lying dead in the airlock when at about the two week mark. I was ready to verify that it was time to bottle, so when I pulled out the airlock to draw a sample, I cleaned, emptied, and refilled the airlock. I'm just now drinking that batch and there seem to be no ill effects.
I wouldn't worry about it-- the airlock did its job.