Was this the last serious derogatory left on your report? If so, you might now be in a new "score bucket", one with no serious derogs.
For scoring purposes, we are all compared with consumers with similar credit profiles --short history or long, recently seeking credit, collection or no, public judgment or no, other serious derog or no. These different categories are nicknamed "score buckets", and they allow you to be compared with your peers, instead of with a 70-year-old who has had credit for 50 years and has never done anything wrong, even once. Otherwise, we'd all be stuck at the bottom of the score ladder.
If this was your last serious derogatory --no collections, no judgments, etc left-- you might have gone through this re-assignment. It's really discouraging when it first happens, and I wasn't at all happy when I lost my points, but I found that my scores recovered and then quickly took off to a much higher level than they had been.
Alternatively, it's something completely else, like suddenly one or more accounts reported high balances, etc. Click the button at the top that says "New - Credit Education", and then read Credit Scoring 101, stickied up at the top of this page, or at least the first post. There's a lot of different stuff that goes into your scores, and while you're figuring it out, it's easy to go quietly (or noisily) nuts.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007