Yamaha 1300 Tourer - Yamaha 1300 Tourer Fansite

I have 1300 with 3700 miles on it. I recently notice that their is a viberation I can feel in the floorboards at certain rpm's. It occurs at the following speeds for these gears: 3rd gear 35 mph; 4th gear 42 mph; and 5th gear 51 mph. It only happens at these speeds, speed up a little on slow down a little and the viberation goes away. Has anyone else notice this on your bike. Thanks Fred