I'm guess you have RAV installed as well.
I'm thinking the "update was not needed" message is related to your RAV signature update.
I also have the following in my log:
/etc/cron.daily/supdate.cron:
04:46:41 URL:http://ftp.ost.eltele.no/pub/www/proxy/squidGuard/contrib/blacklists.tar.gz [547110/547110] -> "blacklists.tar.gz" [1]
Your downloaded blacklists.tar.gz file is probably in /usr/local/squidGuard/downloads. Mine is dated Dec. 1... the same as the file at the site above. So, I assume it is working correctly.
Hope that helps.