HCA: Hermit Crab Association

One of my medium sized hermit crabs molted a little longer than a month ago, and about 1-2 weeks ago he and another bigger crab both went under again. I think the smaller crab isn't molting, since he just molted recently, but the big one might be. They usually don't go under for so long at a time...their food has been untouched too. If the smaller one isn't molting, what's he doing under there for so long? Should I be concerned?

He could just be hanging out, or de-stressing, or it is possible he is molting again.
There really isn't anything you can do other than keep the tank conditions correct - so don't be too stressed about it.