You can't book a King room as it not separate category unless you book a Graden Room - Club Level access since they are all King beds.
It is possible, and we have been assigned a King room a couple of times at the BWI when they have been very busy even without requesting one when we have only be traveling as a couple. Since you can't book a King room, it is always only as a request. We actually like the King layout since it provides more space in the room.
What view is your reservation for at this point?
You can always stop at the Front desk, and request a 2QB room if you have not already noted it on your reservation in advance. Also if you get your room notification via SMS txt, you can also call the number listed in the message.
Dave