Nothing I would worry about. Sometimes you get a wad of guts, many times they squeeze the poop right out of the rat. It's not going to hurt the snake, just remove it from the cage. If you have a really big mess you might have to remove some or all of the substrate in the cage.
At least once per month you should remove the substrate, disenfect the cage (I suggest Chlorhexidine solution or F10) you need to let the disinfectant sit for 20-30 minutes, then wipe it up, finally put new clean substrate in.