10. Wasn't sure whether other rider was waving or making an obscene gesture.
9.   Afraid might get frostbite if hand is removed from heated grip.
8.   Has arthritis and the past 400 miles have made it difficult to raise arm.
7.   Reflection from etched windshield momentarily blinded him.
6.   The espresso machine just finished.
5.   Was actually asleep when other rider waved .
4.   Was in a three-way conference call with stock broker and accessories dealer.
3.   Was distracted by odd-shaped blip on radar screen.
2.   Was simultaneously adjusting the air suspension, seat height, programmable CD        player, seat temperature and satellite navigation system.

And the Number One reason Gold Wing riders don't wave back:

1.    Couldn't find the "auto wave back" button on dashboard.