Good for you!
I recently almost missed a connection in ATL. I was last one to board an MD88 and the FA told me I had to gate check my bag since ALL overhead space is gone. I said it fits under the seat and he said no, have to check it. OK, gate checked it and went to my exit row seating. There above me was plenty of overhead space and below was plenty of space since the seat next to me was empty. When the FA walked by I asked if my bag had been checked yet and he said yes, too late. When I deplaned I realized it was not "gate checked" like on a Barbie Jet, but had to be picked up at baggage claim. Rats!