Have had something vaguely along this line happen twice. Common factors for me: buying last minute, buying for another person to fly. I had to go to a DL ticket counter and show the physical credit card prior to their flight. The OP didn’t have the credit card. OP was then able to cancel the ticket and itinerary and rebook on the spot via the phone line for a fare that was only $40 different. So that tells me the original ticket was also likely made close to departure.