I may be part of the problem. I was in Corvallis and Bend Oregon a few weeks ago and a black 5th gen passed me. My wife said, "he just waved at you" but it was too late, i missed it. I'm not use to 5th gen guys doing the wave.
If I see a modded Toyota, I generally wave. I'm just not use to getting the wave back. There was a very nice 4th gen in Lakeworth TX, I must have waved to him 15 times in the last 4 years...NEVER got a wave back.
I say, wave....... if it reciprocated, GREAT.... if not better luck next time.