Well, Ive been thinking about this all day and evening, and I think, maybe, since he was out of the very first hatch I did, that perhaps he must have had a very faint head spot that I just missed. After having many more hatches, Ive gotten pretty good at spotting even faint head spots. But what still confuses me is that the first feathers didnt grow out barred. Maybe the feathers were too light to see the barring. At least he's found a good home where he'll be matched up with some barred rock hens.
edit:
Now in looking at my own pictures, I can see very very faint barring on the older feathers. So I guess it was my mistake all along. Cant fool genetics.