I have never ever seen this happen before. I just fed Monty, and I looked down after throwing the box away and saw this (that's the mouses blood not Monty's... I am gradually trying to retrain monty to eat f/t (this one was live). I know its obviously a possibility, but is it normal? I have a tank cleaning scheduled on Tuesday or Wednesday, so I will be scrubbing the sides of his tank to get the scent of blood out of there (best product for this??)

Maybe its because he had the mouse pressed against the glass?