Plane left one half hour late. I had a small wheeled carry-on, the size that absolutely fits into the air canada carryon size requirements and it was not completely filled, which I use to avoid checking a bag and not have to go to baggage claim, and thus get out faster to get to the car rental. The gate agent made me check the bag, even though others around me had fatter bags, which they WERE able to fit into the overhead compartments. So I indeed had to go the baggage claim. My bag was there, but it defeated the whole purpose of a carry on. I was not pleased.