I had the opposite problem once: I had a largish duffle-style bag to carry on. It was my only luggage, and it fit in the carry-on size checker box. The gate agent told me I’d have to check it before boarding. So I took out half the contents and another bag that was inside it, and voila! Two carry on bags and no hassle from the gate agent.
To follow-up, I travelled with my carry-on limit bag and a full school-sized backpack and no one gave me a second look when I didn’t check anything. So no worries.
Don’t give them ideas.
Definitely. I fly in a lot of smaller planes, and I can’t stand up in most of the aisles without stooping. There’s no way I’m going to hunch in the aisle waiting for everyone in front of me. I prefer to stay seated until there are only a half-dozen or so people in front of me, and then stand up and grab my case from overhead. Everything moves nice and smooth.
Of course, by the time I’m ready to stand up a bunch of inconsiderate twits from the row behind me have already crowded into my space and made it very difficult to get up and grab my bag. Grrr. Wait your stinkin’ turn!