LAX today and there was no mention of carry on sizing.
While Waiting to board in First Class line decided to check out sizer by door. GA asked if it was in the way , if so, they would be happy to move it. I laughed and said I was just checking it out and wondering if it sustained damage from people trying to remove their bags from it. They pulled it behind door and out of the way. Plenty of larger bags were coming on board. With summer travel and end of holiday week of traveling, I guess they just want to keep everyone moving and departing on time.