Slight variation on the theme here...

I had a flight a couple of days ago, it was almost completely booked. I had an exit row (E+) aisle. There was a GS member in the window who got called up to F, so the guy next to me (in the middle) moved over. Great, I thought - a pleasant flight now - plenty of space to spread out.

Well, before we took off, some (huge) guy came back from somewhere behind us (not E+) and just stated "I'm going to sit there" - not rude, but certainly not a polite "do you guys mind if I sit there" question.

Think I should have told him to ask the flight attendent? He may have not had an E+ capable ticket (or status). That would have been kind of a jerky thing to do, but instead I suffered the cramping for the next four hours.

What would other FT'ers have done?