okay...I think I was a little overboard in my description of the film!
My car is black, so the film was not so much visible as it was tacky to the touch. It felt like a fine coating of crusty debris over the paint surface.
The clay took it off just fine, so no issues, it was just more debris than I'm used to seeing on the clay!
It was all over the bumper above the exhaust and on the rear deck lid face - i just don't ever remember noticing this while doing "spring cleaning"...but perhaps i've neglected this area too long.
I guess I'm going to have to clay EVERYTHING from now on, not just the horizontal surfaces.
gr