Airplane emergency exit row seats

This was a few years ago. I was on a Southwest flight. If you're not familiar with Southwest Airlines, they don't have reserved seats. When a passenger checks in, they're assigned a boarding number. The lower the number, the earlier they board. On this flight, I paid for business select and had boarding A1, so I was first in line to board the plane. However, before able-bodied passengers, Southwest pre-boards passengers that need help -- typically people with mobility problems. Pre-boarders are not allowed to sit in the emergency exit rows.

On this flight, there was one pre-boarder, a young woman with no obvious problems. They started the boarding process. The gate agent scanned her boarding pass, and I went about 10 seconds after her when it was clear there were no other pre-boarders. When she got to the plane, she went straight to the emergency exit row -- right where I was planning on sitting.

I was annoyed, so I (just a little more loudly than necessary) said "You're a pre-boarder, you can't sit in the emergency exit row." She glared at me and I didn't know what she was going to do. Fortunately, there was a flight-attendant nearby who heard me and he immediately came over and told her she had to move to another row. She grabbed her backpack and moved forward three or four rows. And I got the seat I wanted.

EDIT: The flight was on a 737-700. On the Southwest 737-700, there is one emergency exit row and the two sides are not symmetrical. On one side, there are only two seats, but no extra legroom. On the other side, there are three seats, but lots of extra leg room. Depending on what you''re looking for, there's only going to be one seat that meets your criteria.

We (her, me and flight attendant) were halfway down the length the plane. We were the only people back there at the time. The passengers that boarded after me me were getting seats at the front of the plane. The only people that heard me were her and the flight attendant. She didn't get embarrassed in front of other passengers.

For those calling me selfish, Karen, entitled, etc: I paid extra to get on first and get the seat I wanted. She brought a doctor's note to get on first and went straight to a seat she wasn't allowed to sit in. She would have been told she couldn't sit in the emergency exit row when she got her boarding pass. It's also part of the gate-agent announcement for preboarders. She knew she couldn't sit there.