This is easy to replicate. Using the TMX thrust-master with the TH8A H-shifter, When you shift gears, up or down it makes you look up or down while in a race. for example: When shifting from first to second, it forces your camera to look down a bit and then snaps back. As if you were to tap the joystick down on a controller. I double checked to make sure the sifter wasnt bound to something that would cause it to do this but i beleive it is just a bug! hope this helps.