That is strange. There is at least one report that I recall of a Plat CC holder getting the notification regarding the change.
I've got a Platinum Credit Card and got a pamphlet in the mail a week or 2 ago with the changes mentioned, but emphasis was on the new partners/new conversion rates. Just a generic brochure.
I haven't received some things that other members are reporting in other threads though, like the new Ascent brochure that details the Virgin Atlantic 15% bonus on points transfer.