Doesn't look like there is too much going on in that general area.Curious if anyone has popped the screen off to see if there is something that can be adjusted? Might be a clip pushing too hard on it or something. Anyone sending one back or replacing there's and want to try it out? Pretty easy to do.
http://appadvice.com/appnn/2015/09/the-usual-suspects-tear-down-the-iphone-6s-and-iphone-6s-plus