I also recently got a Craddock/Bartlein and noticed the gas port was drilled straddling the junction of a land and groove. I wasn't thrilled to see it, either, and I asked him about it. He said it has no effect on accuracy whether the port is centered in a groove or straddling a transition, but that port erosion actually seems to be worse on the ports centered in a groove as opposed to straddling a transition so he doesn't bother with centering them any more.
Don't have an optic yet, so can't speak to accuracy yet. But thought I would mention his explanation about port location as it seems relevant to the discussion.