I have an aircraft switch from Polarized 777 to sUA 777. I know that there is a small possibility that it may switch back in the next 56 hours. The IAD-SFO flight will be on 27 April (this coming Saturday). I selected this flight at booking because I was able to select a Premium Plus seat for free. Now, I am back to a standard E+ bulk seat. Is there any ground to switch it to a B737 at a later flight time because my layerover time at SFO is over 4 hr? Thanks.