I suspect that this would be a rarity, but as sometimes they molt on top of the substrate. I'd be interested in seeing what was "normal" I'm guessing I have one that's about to molt, (yellow/brown desert species) it had curled up for a long time without moving, then this morning it is somwhat stretched out with a slightly concave head (which had darkened a few days ago.) I am hoping this is normal???!?!