I'm also finding that (quick)loading can mess with NPC patrol routines. Specifically, they often just seem to stop moving at all. That's how I was able to destroy the door in the warehouse without the guards noticing. Clearly this is highly exploitable, as you can quicksave at the right moment to make stealing even easier.
I've encountered that as well. Quickloading at the harbor garrison seems to be stopping the AI routines - the guards started to just stand in one spot.
