I'm surprised the Meguiars rep gave you that information. The Hybrid ceramic spray is recommended to be used on top of a wax or other product for best results. Somewhere they have a long forum thread regarding this, but it's too long to find the posts where it was mentioned by Meguiars.
Anyway, that residue you saw, the instructions say to wet the surface, spray a light coat, wipe it down, then when all done, go over the entire vehicle with a strong stream of water, a pressure washer works best. That is probably what you were seeing on the surface, what the pressure washer rinses off. Been meaning to try this on my F350, but haven't had a chance to get it from the store yet. My F150 I did my own ceramic coat two years ago using Carpro CQuartz UK 3.0 and today it still looks great. I waxed my 5th wheel when I got it last month, and need to grab some of this to finish it off before it gets covered for winter.
Thanks for posting, great reminder.