I've had this happen to me before and when I get to the end of the process, expedia says "cannot confirm reservation, try again," or something like that. In other words, just because it's coming up on an expedia or travelocity front page doesn't mean you'll get a confirm at the end of the process.
It's never happened to me with a WDW hotel, but its' happened with Universal recently as I've been planning for an october trip. It has also happened to me frequently on airline reservations. I go to the airline's web site, and a particular flight appears to be gone at a particular price. When I try to get it on expedia or travelocity, it shows up at the old, good price, but then tells me no dice at the end of the process (usually after waiting through three minutes of a "do not hit the back button, wait for confirmation" screen).