got it open and didn't find what I expected. . . .
all the LED's were still working well. Turns out it was thin black foam tape that was not applied properly when the TV was built. It had worked it's way between the LED strip and the diffuser, presumably from the slight flexing the panel experiences when the TV is moved since it wasn't positioned where it should be (was right at the edge). TV was moved VERY gently and never dropped, bumped, etc. but realistically the panel IS going to flex a little when moved.
So. .now the bad news. First, to confirm it was truly the issue I cut out the offending part of the tape. When tested, the dark area was totally gone, and actually replaced with a brighter area right at the edge due to the tape also not absorbing some of the light right at the edge. I replaced the tape (just positioned correctly), and it looked perfect. However, when doing the final alignment of the sandwich of materials that makes up the panel as a whole (there's like 4 pieces), I broke the thin glass LCD when lifting too close to the corner. GAH!!!!!!
I don't expect any love with Samsung, but I'm going to call anyway. The TV was out of warranty (which Is why I took it upon myself to open it in the first place), but the problem ended up being VERY poor assembly on the left side when built. The tape was actually turned over on itself and applied 3mm over where it SHOULD have been for a 5" section. Someone just rushed it. Was probably made on a Friday
I'll report back how much they did or didn't stand behind their product.