Overheard a cheating braggart, snitch or no?

[BlindingLaser]

I attend the University of Illinois, and the curriculum for the Accounting major is such that I share a lot of my classes with the same people. So I'm in a small discussion section, just hanging out on my laptop waiting for class to begin, and overhear Guy telling Girl behind me about one of my other classes. She asks about the teacher, and his comment is "Kind of weird guy, doesn't really answer any questions...he only creates two forms for the exam and is the only one proctoring." He does not explicitly state that he cheated, but a little bit of induction, and he mentions "I need to get my GPA up to 3.0" adds up to 99% that he cheated on this morning's final exam.

The course has grade breaks that can be lowered if the entire class does poorly, I worked my tail off all semester to earn an A, and Guy just sat next to the smart people and peeked.

I have two questions: the first is, am I being peculiarly naive to have not expected to come across this already in my academic career? I always assumed it happened a little bit, and never actually had it happen around me, generally I only heard about academic dishonesty on problem sets and term papers.

Second is, do I snitch? My feeling is that it might just end up being my word against his, that I have nothing concrete (he did not actually say "I cheated on this exam"), and that it's basically not worth my effort. I have some indignation over this, though: this was not an easy course, and I really earned my A (and have some outside shot of needing a slight curve to make sure it's a flat A, which, ironically, *I* need for my 3.0).

Anyways, I'm still in the class right now, I could even just bring it up to the guy, although that seems like an even worse idea, I don't think anything good could come of it. My other thought was, I have a final exam in this class, if he cheats on everything, he'd probably cheat in here, I could mention it to this professor and have her look out for it.

Thanks OOT! Yes, I searched: I found similar situations (Help cheat on SATs, rat out drug dealer) but nothing too similar: this guy is a total stranger to me, and as a result of a bell curve, is in indirect competition with me.