Whew! It wasn't the final drive making the noise.
While running off into the mountains to my favorite eatery, I noticed an odd buzz through the pegs. Pulling in the clutch seemed to alleviate it, but not much. I thought "Uh, Oh! A BMW final bearing getting ready to puke!" So I slowed it down and it went away so I could get through the rest of the 60 miles or so back to home.
I stayed away from the bike for a while and did the wheel wobble check and bought a dial indicator. Nothing seemed out of the ordinary. No discernible looseness was felt.
So I did another run and the buzziness came back - but in the exact same spot as before. "Say what?" On the way back it was getting towards sunset and I noticed the sun had cast a thousand shadows at the portion of roadway the buzziness appeared. Seems the roadway, although new, had some sort of small washboard effect to it. I don't know how they did it, but riding over the mile stretch made me think the GT had a wheel bearing or final bearing coming apart.