Don't know if this is different in 10.10.1 (Just switched to OSX a month ago so I have no prior experience with OSX)but this key-combo doesn't lock the screen,

Don't know if this is different in 10.10.1 (Just switched to OSX a month ago so I have no prior experience with OSX)but this key-combo doesn't lock the screen, it starts the screen-saver. If you want it to lock the screen you need to change your preferences in security and change the screen lockout time to "immediately" for it to act as a lock.