I booked through our corporate agent (AMEX) a US-operated UA-coded flight. Even though neither the AMEX nor the UA website let me select a seat, somehow I ended up with a Choice Seat on the US system.

Should I just not touch the reservation and hope the seat assignment will stick? (If there is a chance that the US system will remove me, then I would grab an aisle seat further back before they run out.)

I am Star Gold (UA 1K) but that does not really matter flying US when it comes to Choice Seats.

Thanks.