You're completely on the money about why that happened, she is catching on the classroom sign, which even though it's above the level of the player was still impassable to other events. Someone else found it and I've already fixed it and re-uploaded, so if you haven't already got past that point, just re-download. If you have, there's no reason to worry as that's currently the only bit in the whole game that can produce that exact sequence of events.
I hadn't thought of using fast travel to bypass the bad girls event, that's quite enterprising of you! I'll have a look and see why you couldn't just give them their money back though. That's supposed to be an option.
Thanks for the reports, and keep enjoying the game ^^