Bump on nose?

Well, before you ask, he's already got an appointment set up for the vet for next Tuesday (the earliest they could fit him in).

My adult male hog island has developed a weird bump on his nose. It had to have happened within the last week or so, since I try to handle all my snakes at least once a week. I didn't notice it while checking his water etc, but when I took him out yesterday, I noticed he's got a fairly large bump protruding from his nose almost between his nostrils (but further back than that, and a little off to one side). On closer inspection, it looks like there's a tiny scab at the very front of the bump. The bump is big enough to make his mouth open a little on the one side... poor guy!

He doesn't seem to be having any problems breathing, and I'm reluctant to feed him without knowing what the heck that bump is. Could it be a nose rub that got infected? I've got him in a Vision, so not sure what he would get a rub on... The only other things I can think of that would have happened would be him somehow getting a sliver of his aspen bedding stuck on his nose (I replaced his bedding yesterday with CareFresh), or possibly if he struck the glass of his cage at some point (which isn't likely). The wound is dry, just looks like someone shoved a small ball under the skin on top of his nose. It looks uncomfortable but he's not wheezing or holding his mouth open, and he let me touch it without freaking out. I haven't tried inspecting the inside of his mouth.

Any ideas? I'll feel so much better when I get him in to see the vet... I'll post a pic later this evening.