I boarded at the last minute on an A319 & rounded the corner to a late 20 something male sitting in my seat 1B. When he saw the confused look on my face, he asked if it was my seat and if I wouldn't mind switching as 1A was his 12 year old sister. I agreed, as keeping minors with parents or family is something I generally agree with. They were late upgrades, so they were split across the cabin. I ended up in 3E with under seat storage for my backpack, so that was a plus.

The only downside was I had to "remind" the FA during meal selection (my choice had run out) that I was 1K and if anyone was not going to get their 1st choice, it would be the gentlemen now sitting in my original seat 1B (He was not 1K).