I've noticed my Spider ball has that recently too, only where she has been curled up all day and her body folds up on its self to conform to her hides. Doesn't bother her, pretty sure its just from them being curled up and their scales bending to the way their body is bending.
I do plan on getting my BP some bigger hides soon though, she has gotten chubby and almost pours out of one of hers.


Shifty