| Not sure this is a deviation or error...but,
on this 1971 'Cuda vinyl top car, the roof seam areas were painted with a band of white topcoat paint under the Hemi Orange finish color. They were both definitely factory paint. My best guess is that it was a marking to let the painter know that the roof didn't have to be painted. (Vinyl top cars just had a primer coat under the vinyl top.) I've never seen it on any other cars, so it could've been an isolated case or maybe there are more out there...