Make sure you haven't washed your towels with fabric softner or had dryer sheets in the dryer. I have seen a "softened" towel cause haze when my wife was trying to "help." (Guess I should do my own laundry
I have had a couple of occasions where I have gotten a little haziness on my Black GTP exactly as you described. Only in certain lighting and only looking down or parallel to the side panels.
It seems to have happened only when it's very hot and very humid when I have worked on the car. Usually I have been able to go back over that section with a very fine mist and a fresh towel and remove the haze. When that hasn't solved the haziness, and a good washing, as Admin suggested, has not solved the problem; I have taken it as a sign that I am reaching the product overload point and need to get back to a fresh surface.
If you just want to get back to the beginning ..... I would use Mothers Pre-Wax Cleaner that is Phase 1 in the California Gold line. It is designed to remove wax and oxidation and prepare the paint for the next step. I would not use Dawn. Others may disagree, but I just don't think it ever belongs on a car.
Following the Pre-Wax Cleaner, I would use Reflections or FX and then Top Coat.