Damage inside lug recess area, help.

I just received a brand new 5.56 LMT MRP upper, and the first thing I did was look down into the bbl extension/lug recess area, and I noticed something odd.
There is a little "toolmark" or dent/ding on the back wall down inside the lug recess area. In other words, if I am looking down into the bbl extension/lug recess area, with the bbl pointed away from me, as if I were firing the weapon, this "toolmark/dent/ding" is on the back wall of the bbl extension, at the 11 o'clock position.
IF you stick your finger down into the bbl extension, and touch that back "wall", this is the are I'm talking about.
Another way to describe it's location, is if you take notice of the little round circular "ring" of chrome lining, that is on this back wall, then the damage I'm referring to is just outside that "ring" of chrome lining.
Again, this "toolmark/dent/ding" is on the back wall of the lug recess area. I'm NOT referring to the side walls that are rounded in the bbl extension, but rather the inside "wall" or "flat". I THINK if you were to unscew the bbl extension, the damaged "flat" area, would be part of the bbl itself.
IF the flash hider was pointed down to the ground, and the chamber pointed up into the air, the TOP flat surface around the hole of the chamber is the area I'm referring to.
Can anyone tell me if this can be considered strictly cosmetic damage, OR is this going to cause a function problem with the rifle?
Could this cause some type of SEALING issue? I mean, I'm not an expert on how the bolt works in an AR15. Does the bolt itself EVER come in contact with this back wall to create a seal of some sort? OR does the bolt never even contact this area?????
I'm just trying to figure out if this is going to be an issue, or cause any problems.
The little dent/ding I'm talking about, is almost like someone dropped the bbl onto the ground, or it might be a little toolmark from a milling cutter.
Not sure. It's not a HUGE CHUNK of metal missing. Rather, it's a little toolmark, which almost looks like some funky shaped stamping in the metal. LMT has advised it's not their stamping mark or anything like that.
I just wanted to ask everyone's opinion on this matter?
It's just not something one wants to see down inside his lug recess area...
Thanks for any help.

You might try removing the barrel and taking a nice close picture (use the macro setting on your camera). I will look at my MRP when I get home but it would be very helpful to see the actual concern.