Oh GREAT! My AMEX SPG card is new. I have had it just over a week. I ordered $3,000 worth of coins and got an email today saying that it is backordered. I sure hope they don't cancel mine.
Do you mind me asking how new the card was that you used and how much you tried to buy from the US Mint and how long ago you placed your order?
Has anyone else had this problem? Do you usually have to have the card for a while before you can start purchasing coins?