yeah, a coworker of mine. she got on the bus, and sat in the back. Her best guess was that one of the other passengers saw her sit in the back and figured she wasn’t paying attention to the bike. Luckily, it wasn’t an expensive bike, or her only bike.
I always stay near the front of the bus when I can, to keep an eye on my bike.
It might be worth rigging up a test to see if PAT can help track down a situation like this. Get two friends and one bike. Person 1 mounts the bike. Person 2 gets off first and tries to take the bike. S/He either succeeds or does not. If so, we then try to pursue things with PAT to see if they can track down some info. If not, we explain the bluff.