This same thing has happened at other Hiltons. There is a thread relative to the ADT doing the same thing. After contacting the Diamond desk, they have changed many of the nights back to standard awards. In the case of the ADT they were asking over 100K per night for a "King Plus" room that had the exact same description as a King room.

I know this type of "pricing" activity has driven me to Marriott and SPG. My wife and I tend to use points at the higher level hotels and since they are now pricing out at 3 to 4 times the "normal" rate (even 11 months out). I refuse to continue to stay at a chain that will play these games.