Haunted bus?

Getting into my last stop of the evening, I unload the last of my passengers and do a walk thru to ensure there isn't any lost property. Seeing as the bus is empty and devoid of any interesting articles that someone has left behind, I hop back in the drivers seat and continue on my merry way back to the depot. A couple of blocks later I hear the bell chime. Confused I look down at my dashboard and see that indeed, the next stop light is illuminated. I pull into the next stop and check the bus once again for forgotten passengers. I am greeted with an empty bus. Electrical malfunction or bus possession?