I just picked up a 2008 JK Unlimited Rubicon. I noticed that when I press the gas petal, in addition to the “normal” engine sounds, I hear what can be described as a rattling/buzzing sound or a sound you would get if you put a playing card between your bike spokes and spun the wheel really fast. I only hear the sound when I press the petal, and I replicated the sound when I was in park in addition to being in motion. It sounds like the noise is coming from the dash area / just behind the dash. It does become louder the further the petal is pressed, but it’s often muffled by the engine noise. Is this a normal sound, or should I have this checked out?