Wow, thats quite a drop! I believe the status change should take affect on February 28. That is my interpretation from the US website:

http://www.usairways.com/awa/content...toqualify.aspx
"Example: If you are a Gold Preferred member and you have at least 75,000 Preferred-qualifying miles on June 1, 2008 you will be upgraded to Platinum Preferred status immediately, and you'll maintain Platinum Preferred status through February 28, 2010. "