When we booked I thought there was something in the fine print that stated that until your vacation is paid in full, prices are subject to change. Glad I paid in full already.
This was copy and pasted from my reservations
Terms and Conditions
Effective for arrivals January 1, 2011 to December 31, 2011.
Prices
All prices are in U.S. dollars and are subject to change until package is paid in full. After package is paid in full, package price is subject to change due to imposition of taxes or other charges of governmental authorities. If air transportation is included in the package, the airfare is not guaranteed until paid in full and the tickets are issued.