Originally Posted by
povertyjetset
I asked an AA agent on a subsequent flight if this were common and was told they would never force someone to change seats unless it was a safety or medical issue.
AA absolutely moves pax out of confirmed seats, for all sorts of reasons, as does pretty much other airline in the world.
Seat assignments are never guaranteed. If you're moved from a seat for which you paid extra, to an objectively inferior one, you might be entitled to a refund of the fee paid. Otherwise, no way.