I've looked at a few spams that I have received today, and compared the URL's found in them with those listed on SURBL+ Checker. Even though some of the domains are listed in those lists (eg, URIBL: multi.surbl.org: listed [Blocked, sectility8symposia.com on lists [sc][ws][jp])) they are not necessarily being caught as spam, or at the very least not scoring as high as I would like them too.
That alone isn't too surprising.. SURBL is highly dynamic and the URL could have been added after you got the spam, but before you made a check.
In fact, I cannot see anything in the headers that leads me to believe that SURBL is being used/enforced.
That said, you can always check manually by running a message through a copy of spamassassin -D and watch for the checks.
Look for lines like: URIDNSBL: domains to query: xxx.com
