Safari Scrolling Noise

I purchased a Retina Macbook Pro about two weeks ago. When I use the trackpad to scroll in Safari, I hear a kind of buzzing or ticking sound. It's not a huge issue, though it can be a little irritating when I'm in a perfectly quiet room. However, the interesting thing to me is that when I scroll through my documents or even in Firefox, this does not happen. I am led to believe that this is a problem in Safari. Does anyone know what could be causing this? Is there anything I can do to stop it?