Sorry I added this using an old browser and cannot layout this properly.
Fix: add this to /etc/sudoers using the visudo command
"Defaults:ALL timestamp_timeout=0" (without the quotes)
This prevents the login-without-giving-password. It's safer anyway. I think Apple should make it the default anyway.
Note: of all Mac OS X users, how many use the command line (Terminal, probably negligible) and how many of those use sudo (probably the majority of that small group).