Well I got the answer to my above question yesterday. The noise was becoming more frequent and while I was underneath it checking for anything loose, I saw axle grease slung on everything around the drivers side axle due to a torn boot, no idea how that happened. Took it to the dealership, the tech heard the noise, checked the fluid and it had lots of metal in it and it was just changed 3000 miles ago during the rear diff bolt fracture recall. So the tech started tearing into it and I his words "the rear diff ate itself". So now I'm getting a new diff and axle under warranty.