Hmm. Actually it does still look like septicemia a little. Or maybe the septicemia left permanent marks. Based on his gorgeous pearl coloring, he doesn't really look like the kind that would have natural red markings on his head so I do think you are right, it is related to the septicemia somehow. But it doesn't seem to be bothering him. Since he's still on tetracycline and AQ salt, if he does have a problem, both of those should help to clear it up. If, after treatment, it doesn't go away but it doesn't get worse or affect him at all, then I would say it may be scarring or something like that.
He is so darn handsome. I really love that pearly color of his.