It's a glitch.... the rate is not valid anymore (but apparently still shows up in the general screen).
Limited time - Rate Description:
Reduced Rate:Tax Excluded: - Booking Window: 19DEC12-26DEC12 - Valid Stay Dates: 01JAN13-28FEB13 - Full prepayment due at booking - Non-refundable if cancelled
However if you choose for example Jan 3/4 the rate still is available..... that's how I saw it before.