Yum -clean all........is that a bad thing?

[Neal Wilkinson]

In an effort to keep things neat I noticed this option and ran it. Now
however when I go to get and update then I get the message (No Packages
marked for Update/Obsoletion). Up2date says there are 4 available. I
normally check for updates with it and then apply them with yum. So have
I screwed up what Yum knows about the system by doing a -clean all? If
so how do I repair it?