My 2007 has developed an odd vibration in the handlebars. First, the bike has only 8500 miles on it, and until recently was glass-smooth. The vibration is a resonance that cycles left-right, left-right, from one hand grip to the other, back and forth in a cyclical manner. Most noticeable at interstate speeds and higher. The chain has developed a tight spot in it, and I wonder if it could be the culprit? Still, only 8500 miles and I lube the chain religiously. Hard to believe I'd need a new one so soon. I usually get 15,000 miles or more out of a stock chain and sprockets. Pulling the clutch in at speed reduces the intensity of the vibration, but it does not stop completely. It's really annoying, since the bike used to be so smooth. Any ideas out there?