Based on the nickel boxes I used to do, I'd get about one war nick for every $100 of nickels I went through. So, 1 out of 2000 nickels in circulation is a war nickel. That's with boxes though, honestly I think the chances of getting one in change are even less, since I've received many more than 2000 nickels in change and have never gotten a war nickel. So far my only silver in change was a 57 roosie. I'd say you beat the odds, nice find!
Ok, so I read up on the 1942 not always being a war nickel. I didn't know that; there is no mint mark. But I try to be a stand up guy and admit all my excitement was for not. It was an honest mistake.
I would like to thank the buzz kills out there for furthering my education.