Buzzing Sound When Auto-Brightness Is Activate?

My phone is pretty much perfect save for a buzzing sound when auto-brightness is active and my screen is on. It's very noticeable when I'm making a call. I'm assuming that it's coming from the camera. In most cases, I have auto-brightness disabled. However, I am worried that the buzzing sound is a symptom of a much larger problem that I have yet to run into.

Is this a widespread problem, or did I pick up another lemon (this is my second unit as my first one had some dead pixels)? I am still within my 14 days, so if I have a bad phone, I'd like to return it while I still can. However, if this is a widespread problem, I'm OK with it since I can live with manual brightness...