Well, the best place to look for mites or lice is under they little arms, and around their vents. (butts)

It's possible that's what the problem is but it does sound like a molt, they sometimes have a partial molt and it does seem to happen either in the spring or fall just like the more major molts.  Some of mine are actually looking a little bald this spring too but they're improving now that they're out in the sunshine more.