When I turn the ignition on my 2009 Traverse and back out of my driveway and then proceed forward I can hear two noises which sound like their coming from the front end area when the vehicle reaches a[/color] speed of exactly 15mph. It happens everytime. I don't know if this is a switch or something activitating or ? It only happens after the vehicle has been turned off and then restarted. I've only noticed it upon backing up and then going forward. The noise is not heard when I am on the road stopped at a light or stop sign when I proceed on and reach 15mph. Anybody else heard this noise or have an idea if it is normal or not?