HCA: Hermit Crab Association

Ok, I'm not sure if I should be concerned about this or not... Or if any action is required... So some advice would be greatly appreciated!

About a month ago I upgraded to a 70 gallon crabitat and shortly after being put in, my large PP, Cookie, went into a cave and dug under (hasn't been up since - I believe he's molting). Two weeks later, I put 3 new crabs into the tank after their 2 week stay in iso was up. Recently, I've noticed that Curly (one of the newbies) has been digging around in the cave where Cookie initially went under. He doesn't dig down very far, just makes himself a shallow nest to rest in during the day. My question is: Should I be concerned about this? Could he be caving-in any of Cookie's air tunnels or anything like that? And if there is a problem, what can I do to fix it?

Thanks in advance!!

My E's did that to my PP's who were under. George came up 3 weeks later with no problems. Bash has been down since Aug 16 and even with all the action Toby digs in the tank, he hasn't bothered him that I know of and no dead fish smell in the tank. Cookie might have gone down there but could have dug over to one of the sides, I wouldn't worry too much about it from my experience that is. Hope this helped to ease your mind.