Read permission of /usr/share/mime changed after update

After several updates of my opensuse 11.0 system via “zypper -dup” the /usr/share/mime were no longer readable for users wich leads to a lot errors in KDE 4.1.

After running update-mime-database everything works as before.

So the question is why are those permissions changed during the update and if this is normal why isn’t update-mime-database executed by default after the update?

Hopefully someone can help me