Warning: RPMDB altered outside of yum.

I got a warning message while installing Webmin/Virtualmin, similar to this thread: https://www.virtualmin.com/node/22850

My server is running CentOS 6.4 32bit, and all I typed was "sh ./install.sh" according to this page: http://virtualmin.com/documentation/installation/automated

Most websites (including this one: http://www.ehowstuff.com/how-to-fix-warning-rpmdb-altered-outside-of-yum/) say you should either type "yum clean all" or "yum history new" to fix it (both of which I did try but they didn't seem to do much of anything, or if they did I still have no idea if they fixed the problem).

But also at the end of the installation itself, it does say "INFO - yum clean all" (just like in the thread mentioned above: https://www.virtualmin.com/node/22850), so did it fix the problem itself? Or do I need to try something else?