Whenever I get a libnotify popup telling me that I have security updates availible I always end up going to the packagekit icon so that I can review my updates to see what exactly they're fixing and also to pick up any non security related updates as well.
It would be quite helpful to have the show updates action available from the icon left click menu as a button in the notification as well. I would assume that others like reviewing their updates before applying them as well.
We moved the upstream bugtracker to GitHub a long time ago. If this issue still affects you please re-create the issue here: https://github.com/hughsie/PackageKit/issues
Sorry for the impersonal message, and fingers crossed your issue no longer happens. Thanks.