Yes that does sound like a software bug. A good reason to have your foot on the brake before you reach for the start button. I suspect if you press start without ever touching the brake pedal you will get the "press brake to start" message as expected, but stepping on the brake JUST after pressing start may be a condition nobody thought of testing. It would have been a good "boundary condition" to test though. When I was working as a software test engineer, one of my colleagues said there are two things you don't want to see being made, sausage and software.