Tried another wash, made no difference. The ceramic coating was applied a little over two weeks ago, and I was advised not to wash the car for 1-2 weeks, this was the first wash 'after the fact'. Now, of course I did review the car when the coating job was finished, and I don't recall seeing this problem even out in the sun, but maybe the coat had still not fully cured and either I glossed over it or it wasn't visible back then and got worse over time. The tricky thing is that it only shows under natural light, I tried LED, halogen, incandescent, nothing gives the spot away indoors, it's only revealed by sunlight and even that only at certain angles (but then it's bad, worse than the photo would suggest).
So eventually I called the installer and, along the respectable lines of what you're saying, Shane, he was honest and said it was possible that the coat overran a bit in that area, which can cause a similar slight difference in color. Then told me to take the car in, he would take a look and chances are he can fix it with nano polish and a reapplication of ceramic pro light, or if not, he'll polish the ceramic coat off and redo the hood from scratch.
The shop and I are both pretty busy, so it will take at least a week before this gets solved, but I'll post back, if only as a reference in case it might help others in the future.
Thanks a lot for all the advice and pardon me the lengthy posts, I'm trying to curb my linguistic diarrhea even if it doesn't always show