Results are in.
I had the upper in the shop for a few minutes, checked some things out, and it appears that the front sight base is canted.
It's about 1.5mm off to the side. We eye-balled it, then used a straight-edge for comparison.
The front sight base is pinned on using tapered pins, so there'd be no adjustment possible at the front end, and there's no slack in the rear slot (receiver pin) to allow any movement.
So, ArmsEast has agreed to take it back, and send a new upper.
BZ to Arms East.
NavyShooter