LOL! Unfortunately, I was the one who did the tampering.
I was experimenting with different locking techniques last night, and I ended up with the U-Lock through the back wheel and seat tube, and I also had it around one of the crank-arms. It seemed like a pretty reliable way to lock it up, because the pedals won't move at all when it's like that.
Anyway.....I don't really know what happened, but the lock ended up getting stuck between the crank arm and the crank. Also, the lock was being pushed on by one of my spokes. I couldn't turn the pedals forward because the spoke was in the way, and I couldn't really turn them backwards without damaging my lock or crank (or both). I had to get the lock out, so I ended up applying extreme pressure to both pedals to force the lock over the crank. The lock DID come out, but the rubber sleeve over the steel is all torn up now, and the little attachment they put on there for me to put it in the little holder was thrown across the room after leaving a big scratch from the retaining screw.
So today, my lock looks like someone tried really REALLY hard to break it but failed. I suppose this is extra thief deterrent, because it appears that someone already tried and failed.
There's no moral to my story. Just that if you ever try to experiment with locking techniques that you don't end up doing something that gets everything stuck.
I still don't know exactly what I did.