It means you did the update on your DB, but then you went to post your next new gallery, however, you forgot to 'generate' on the site's page. So your DB essentially is not showing as up to date and causing that problem.
It's been doing that for a month or so now. It threw me for a loop the first time, but I figured it out. Have forgot a time or two since. You just have to remember to re-generate after a DB update sire.
