If I have a simple form with validation (identical to the live demo) but with a calendar control on it. When the user changes month or year the errors disappear. Is this a known bug?
Those are the bug fixes for 3.1.1
http://labs.jboss.com/auth/wiki/RichFacesWhatIsNewIn3_1_1
If you find something similar to your case, this is fixed in the 3.1.x branch. If not, return back and post your code snippet.