> Is it possible that Fedora has some sort of regular checking on the
> background or even cron job that would query the RPM base?

There is, but only if you have installed yum.

Other than that there is also ksmarttray that asyncronously accesses the rpmdb
through smart invocations, some (smart update) even as suid root. Could that be
an issue? I don't know if the reporters were using ksmarttray, but if it's a
possible problem I'll check on them.