HA...a couple of years back I had a return ticket for the day before my passport expired. Air Canada was actually the one that questioned whether I could get into Jamaica without incident but they quickly checked & I was good to go! Came back & it took me forever to renew it (stupid paperwork)...but that's another story.
There weren't any problems from Canada or Jamaica's side...not sure if it's the same for the US...would definitely confirm this...