It is possible, that at the time you order your tickets certain seats were reserved, but the time frame wasn't met and they are then up for sale again later, which is why you didn't see them as available. Unfortunately we can't predict or influence when or how much this will happen. Please note that we can't accept any trade requests related to better seat options. Therefore make sure you are satisfied with your seats before ordering them.
Why do you offer better tickets now, and why haven't they been available when I ordered mine?