Hilton made an announcement back in April last year (2014) (access here) that they would be moving away from yearly award category changes and would adjust award categories “seasonally” that seems to roughly every other month based on the observations.
Hilton HHonors has just updated its web page where they post these changes. I doubt that they would email Hilton HHonors members about these “enhancements”.
You can access Hilton’s web page for these changes here.
You have to bear in mind that Hilton’s award categories don’t mean as much as they used to because the number of points within an award category varies a lot and can be changed unannounced.
Here are my pieces in 2014 about award chart changes during the year:
Here are the properties moving up in award category:
Here are the properties moving down in award category:
Here are new properties added to Hilton HHonors and their award categories:
There are 14 hotels moving up in award categories and 10 moving down. I stayed at the DoubleTree hotel in Nungwi couple of weeks back in Zanzibar (paid stay) that decreases to award categories to 4.
If you are planning to book any of the hotels that are moving up in award category, you should do it before the April 8.
For award bookings for hotels that are moving down, you should do them once the new award pricing is in effect. If you already have a reservation for one of them, just contact Hilton HHonors after the change and they should be able to reprice the award.