[CentOS] Fun with nosetuid!

On an unpatched Centos 4.4 system I chmod'd /usr/bin/sudo to ug+s, and set 
the filesystem in /etc/fstab to defaults,nosetuid.  Reboot, and am told 
sudo needs to be set to setuid root.

An ls -l shows rwsrws-- root root sudo

I had to use a rescue CD to undo /etc/fstab for the filesystem partition 
so sudo would work.

What am I missing?

Thanks.

Scott