Frustrating experience today on a flight from Tucson to Las Vegas.

Frustrating experience today on a flight from Tucson to Las Vegas. We are A list and booked Choice Extra seats. We boarded and put our backpacks in the overhead. My bag is a 42 liter Cotopaxi. On past flights I have been told it is too large to be placed under the seat. On this flight we were told we had to put them under the seat to make room for other passengers bags. I asked why she was making us take out bags down when I could see lots of other smaller bags in the overhead bins and she snarkily said “Sometimes it’s nice to help other people”. Not sure how good or bad her day has been today, but it was an unusually poor customer experience. See less