I almost got in a fight on a plane less than a month after 9/11. At the time, the policy was that everyone had to be in their assigned seat with the windows open on takeoff. Some jackass and his whore wife just had to move seats before takeoff (the plane was 70% full). They held everyone up until they finally moved back to their seats. I made a loud smartass remark about how it must suck to have to move further back in the plane because they'll get there so much later than everyone else. He glared at me as he moved to his seat. After takeoff, they moved back to the seats closer to the front. Again, I loudly commented that everyone can rest easy since "they" are back in their spot and will get there faster than everyone else. We had a stewardess that was deadheading back to California sitting with us and she thanked me for saying something because she couldn't. Anyway, the plane lands and the guy gets up and takes a step towards me. I had to bend over to get out from under the overhead bin and when I stood up, he took one look and turned around (not that I'm that big, but he was a manlet). I heard a snickering behind me and a soldier in fatigues said that if he had taken one more step, he was coming over my shoulder and would have immensely enjoyed beating the shit out of him.
Tldr...some jackasses just gonna jackass.
It was weird walking through the airports with National Guard in full combat gear carrying rifles.