I picked up a brand new 2013 Mazda 2 Venture Edition two weeks ago. Last weekend I started noticing a small, quiet vibration - almost cricket like sound - intermittently. It is only audible with the car stereo turned off but it's noticable, yet quiet. It's more prevailant going over small bumps in the road, but also occurs somewhat on flatter surfaces. It's coming from the front but it's tough to pinpoint exactly where. Any thoughts on what it might be?