Has the Validator changed recently?

To whom it may concern,

I have recently been using the CSS validator to check for errors in my
stylesheets.  About a month ago I validated a stylesheet and no errors were
reported.  Last week I ran it through again and the sheet would not
validate.  The thing is, though, I made no changes to it.  What has changed
with the validator recently?  I notice the report page is different than it
has been in the past.  Has something changed in the specification that would
require me to redesign the stylesheet?  The URI I am trying to validate is
http://www.markzobel.com/style.css  Thank you in advance for your
assistance.

Sincerely,

Mark A. Zobel, M.Mus.
4059 Dawn Court
Boulder, CO 80304
email:  mark@markzobel.com
office: (303)949-8215
fax: (303)786-8823 (requires call-ahead)
website: www.markzobel.com