I get asked that all the time. My last trip, I was asked to prove that I was actually living in the US. Apparently for customs purposes.

But back to topic, I do like that the current check-in kiosks will display the full Timatic requirements and agent will go through it with the passenger. It's as most transparent as possible, arguing with the agent will be like arguing with computer interface. But there probably needs to be a way to better deal with those exception cases like the ones noted in this thread.