Transmission issue

I have a 2008 wolverine 450 SE, and while out running down some trails, I splached through a few, maybe 1ft deep puddles. after about an hour of riding i headed back, and it felt as if the transmission would slip into neutral everytime i hit the throttle. I could start out very slow and eventually get up to 20mph. about 15 minutes into my rad back it got better i could accellerate faster, however any time the rear end would get bouced or shifted right it would slip back in to neutral. I tested that by just fish tailing a couple of times, same thing happened. Any ideas on why this is happening?

Thanks
Matt