Weird Hermit Crab Behavior?

[Deadna]

So I have 2 small (Less than 1 inch in length) red leg hermit crabs, and one medium (about 2 inches long) blue leg hermit crab. Today, when I turned my tank lights on, I noticed that all three were piled up in a crevice, the blue leg on top of the two red leg. Is this normal? They don't appear to be fighting, and my only guess is they do this for safety. I've just never seen or heard of this before. Has anyone else had this?