took machine for a ride this afternoon and started climbing a long hill on the powerline. almost to the top and noticed that there was a very noticeable whine that changed with the engine rpm. I turned around and headed toward home. as I got closer to home the noise had reduced considerably but it was still there. When I got into my dooryard I put the machine in park and increased the rpm on the motor and the whine fluctuated with the motor rpm even in park. Anyone run into this. the machine only has about 30 miles on it. when the engine is running is there a transfer case that is turning, if nothing is turning except the motor could the noise be coming from the clutch. I turned the machine off and after about two hours I started it back up and the noise was gone???any ideas what to check?