Neiman Marcus needs to call your credit card bank the first time you order with them??? Are they worried about the buyer not being able to pay?

I put in a Last Call order and got a message that they had encountered an "issue" in processing my order and that I should call them. They just told me on the phone that they needed to verify my credit card with my bank before processing the order. Huh? I've never had this happen before. With a credit card, isn't part of the whole point that the card company pays the vendor and the buyer pays the credit card company? So does anyone have any ideas why NM does this?