This is more than he had known about Jazz's lifespan, too. But it only made sense; robots didn't grow old the same way.
"I'm... sorry, Jazz," he says, a little unused to the words. "But even when I... did what I had to on Gunsmoke, there was a lot I didn't want to know. And maybe someday you'll be able to ask."
It's all that he can think of to say, and he realizes his hand is running along the steering wheel as he says it. The idea of trying to communicate with a car he is riding in is ludicrous enough to make him laugh... except for the fact that Jazz sounds honestly angry.