Damn. Maybe it's burned into the print after all?
Finally heard back from the seller, and awaiting their findings compared to the screencaps.
BTW, can someone politely suggest this fellow amend his review? Lucas restored the five minutes Warners cut for the post 1977 reissue for starters. I can't believe they are totally oblivious to how much the film really has been changed!
http://www.dvdbeaver.com/film3/blu-ray_reviews52/thx_1138_blu-ray.htm