Pressing "A" to start quickplay lap shifts gears

Hello all,
When I am using quickplay mode with a controller, I push "A" at the start screen to start a lap (as the game says to do). Most of the time, this starts the countdown as it should, but a few times, it shifts my car's gearbox instead, stalling my engine before the lap even starts (keep in mind this is while the start screen is still showing). This seems to happen at random and the best way of replicating it would be to just start a quickplay lap several times and see what happens. Does anybody know the cause of this problem?