Giving the FC seat to the person in 8A was not the correct thing for a gate agent to do, but it is certainly easy for two people to agree to exchange seats.

Just a couple of words of advice to elites traveling with non elite companions:

Always see to it that you, not your companion is assigned the middle seat, that way if you do get split up your companion isn't stuck in a middle seat.

Alternatively If you can get a window and aisle seat assignment, and the middle seat is occupied it usually isn't a problem to exchange seats.