So tomorrow I'm flying a same day MSP-ATL-MSP (1291 and 744), I got upgraded before the window for my flight out so i was in 4A for the outbound and chose 26F for the return. Having checked in earlier today I went back a few min ago and looked at my seats again, and noticed I was no longer in 26F but rather 33E....a middle seat, and my original seat was now gone, and the only other 2 seats that were open were 21D, an aisle which I hate because i try to work on my laptop during the flight and don't like my work files being visible to everyone around me. or 24E a exit row with no recline. Called in and was told yea well sorry, which of the seats do you hate the least? so now I'm stuck in 21D.

Can anyone think of a reason why i'd be booted out of my seat after having picked in this close to the flight time? As far as i can tell there wasn't an equip change. If i complain about involuntary seat change can i expect any compensation?