Has anybody encountered a situation where a Starwood hotel would not accept their own credit card?

I booked an award stay for the Sheraton Luxor and was unable to enter my card number. I entered a Mastercard number instead. I'm thinking that perhaps it was a website issue and that they will accept their own credit card at the front desk.

As an award stay, I'm not too worried about it: worst case, the incidental charges for the stay will end up on my credit union MC. I'll save on FX fees and lose a handful of Starpoints... Not a big deal, but just wondering if people have ever encountered this in practice.