Just watch the wound area for a while. Usually small rat bites will heal up just fine in a shed or two. If a knot starts to appear in the area, take it to a vet cuz an infection from the bite is setting in.
More importantly, KILL the rat next time. Not daze, but KILL it. Break it's neck, and it can't bite your snake. Rats are formidable critters, and possess the ability to KILL your snake.
Here's a thread that may make you think twice about live feeding....
The Live Pile
Hope that helps
Rick