Refer to this
video for the fix. It's basically a small grounding bar (located at one one for the more sensitive locations of the MBP) making metal on metal noise when the bottom case flexes. I would suggest removing it and placing it in a zip lock bag, preferably in a safe place, such as the box your computer came in for safe keeping to reinstall if you ever have to bring your machine in for repairs. This will technically
void your warranty, but as long as you don't damage anything when opening your computer Apple will be none the wiser to you doing anything. I have personally have had in warranty work done since taking the grounding bar off with no issues from the genius bar. Removing the bar hasn't caused any adverse affects either as of yet.