flyinkiwi - your post has reminded me of two similar problems, because the pilot who flew it last didn't follow the usual procedures in shutdown!
Usually flying the tug Supercub, you NEVER use the brakes, as with a heavy 180 hp engine it just loves to nose over! Early days at Booker, getting qualified as a glider tow pilot on the 180 cub, I forgot to make doubly sure that the parking brake, which is a silly little lever hidden down out of sight- and out of mind - beside the seat, had been released before takeoff. Well, one wheel was free, anyway.....and the big power to weight ratio took care of the takeoff, on the wet grass.....but landing was rather a handful as it had one wheel rolling and the other one frozen stiff.... Custom is that the parking brake is never set. This is actually a good idea when parking at the launchpoint, so the plane can swing nose into wind if it wants to. And parking the Cub in the glliding hangar, you don't ever set the parking brake because people who may not have the foggiest idea of where the handle is or what it looks like, need to push the plane out of the way.
The other incident (wasn't me!) was our CFI tried to fly the motor glider when the last person to use it had turned off the fuel..........................we never let him forget that one!