The factory lock is fairly useless (I'm not going into explanation on the interwebs). I can't imagine why anyone familiar with Monsters would even want to mess with the lock since you cant store much under the seat. My guess is you are the victim of a random fool and it is unlikely this will happen again.
LOL it's true. The lock is pretty useless and it boggles my mind why someone wouldn't take the time to examine the setup a little better rather than waste time trying to defeat the lock itself...