Flying DFW- CLT-YYZ yesterday. Flight is very full. 15 minutes prior to boarding, the GA announces that if you are seated in sections 4 and 5, do not expect any overhead bin space, so please consider checking your carry-on, no charge. This was not a gate check situation. Baggage ended up being checked all the way through, no charge. Down side is the waiting time at YYZ for the bags to arrive. So...is the new norm for sections 4 and 5 to be sh#t out of luck when it comes to carry-ons ? Is the solution better policing of carry-on baggage limits, or are they actually overselling overhead bin space? Just askin' .