Is my sisters hermit crab okay?

Mu sister has two hermit crabs. Hamilton and Hoffman. Hoffman hides a lot, so my sister told me to get him out. I picked up his shell, and he's shy, and doesn't come out..So I did And I looked, and where he was shedding of himself. I guess he malted. So I told her and we were like 'I think they're supposed to do that..' So we left him there, but he hasn't come out once since then. It's been since yesterday morning. What's up!?!? When we looked in his shell, we saw a little claw, but it hasn't moved. And he seems a little deeper in. What's the situation?