Older RPMs Not Being Removed During Upgrade

In CentOS 5, when upgrading a minor release of 5.5 (only tested 5.5.30->5.5.31, 5.5.31->5.5.32), if the mysqld server instance is not running, the previous MariaDB-server package is not removed. The server itself has successfully been upgraded.

This seems to only affect upgrading CentOS 5, not CentOS 6, and only if the service instance is not running. This seems to indicate an RPM packaging issue.

It looks to be because of the post uninstall script, as seen by this error:
error:

%postun(MariaDB-server-5.5.31-1.x86_64) scriptlet failed, exit status 3

Attached shows the old RPM still present in the system.

Thanks,
-will