I had the trailer thing happen to me also. Had it disconnected after supper in the evening so that my wife could go and run a few errands. She backed the truck back up to the trailer but didn't hook up the W/D hitch. Woke up at 8am to leave, only to find a ticket attached to the side of the trailer.
I have my suspicions on who did it -- she was probably mad that my 23 footer & truck were (legally) parked on the street but partially in front of their house in "their" spot (even though they have a front driveway also) for all of
one day in the year (trailer is stored elsewhere)...
