My elite status has also jumped around a bit these past few weeks.

I ended 2009 with 45 nights and Silver status.
After the 35 rollover nights hit I became a Platinum.
Yesterday the system was apparently recalibrated and now I'm back to Silver.

I'm not complaining. The temporary upgraded status was clearly a mistake. It would be nice if the issue was communicated a bit better though. The agent on Marriott's Platinum line had no idea of what I was talking about when I asked about the odd status changes.