It's just shedding. They tend to shed their skin in sections, so sometimes the tail will go, sometimes the legs, sometimes the tummy and back, sometimes the head... sometimes the whole body will shed, but I'm pretty sure that mostly only happens when their really little. Your little guy will probably be rubbing on things in his tank, and within a few days or a week, he will have shed it. If you give them a
bath it can soften the skin and help them to shed it a little easier. That is perfectly normal. They shed a lot as they grow, and not so much as adults.