[opensuse-security] rpm database integrity

Hello, at sans.org I read: "The first thing to do is check the contents of /var/lib/rpm. The databases should have a date/time stamp of when you originally installed the system. If you see a different date, be suspect of the integrity of the databases." Well, on my system the time stamp of the files within /var/lib/rpm do not carry the time stamp from original installation, the time stamp seem to be the last time I installed some new stuff with YaST. But, the time stamp of the directory /var/lib/rpm itself actually is the original time from installation. I now wonder, does sans.org tell us something not entirely correct? When you install stuff, doesn´t the time stamps change below /var/lib/rpm ? Thanks