It's not a spot of rot, but rather a small scabbed over cut. Given the size and shape of it, I believe it to be a bite from a rather fiesty mouse he had a week ago. I tried to take more upclose pics, however my camera refused to focus for me.

here is the same pic zoomed in. It is a small line than looks like you or I were to have a bloody splinter.



I usually wait the full 48 hours, however since it was past the 24 hour mark (which I believe to be the commonly excepted minimum) and she was already back to my curious little gal that sticks her head out of her hide and watches me I thought I'd give her a chance. Sure enough when I opened her tank she just looked at me and waited for me to pick her up rather than recoil back into the hide... So I thought why not?