So here's the solution! I took my bike in to the LBS to get their take. After a couple of test rides the culprit was a poorly bent Shimano spring. The LBS said they could spend some time trying to fix the bend or it might be easier to purchase a new set of pads. Since I'm doing a big hill climb (and descent) next week I decided to opt for the new pads. The fix was cheap and no more noise/sound.

Thanks for all the suggestions folks.