Had my first real seat standoff on a flight today.
Boarded and someone was already sitting in the priority seat I paid extra for. I politely mentioned it was my seat and they just refused to move at first. Got a little tense and the person started getting mildly hysterical about it.
Eventually it got sorted out and I got the seat, but it was definitely one of those awkward moments you hope never happens.
Flying a lot, I always wondered when this would finally happen.