This happened to me with a hire car. I parked the car and pressed the button to stop the engine. The engine cut out so I got out of the car, locking the vehicle with the remote as I walked away. After some time I was contacted by the security team of the company I was visiting to tell me the engine was running on my vehicle. The auto engine off had kicked in as i pressed the engine stop button, but because the engine had stopped I didn't hold the button for long enough to actually switch the engine off. When I locked the car the turn indicators flashed with a non-standard pattern to warn that the lock had failed (because the engine was not off) but because it was a hire car I did not recognise it. When I drove the car home the same thing happened at the end of the journey but this time I was expecting it and switched the car off properly.