It isn't just where there was a bit of paint left but also where the ospho puddled or got laid on thick.

I got a quick response back from ospho this morning and this is what they had to say.

"The Ospho is trying to get through the paint to treat the surface and it
will break down the paint and could cause a greasy or tacky surface if that
happens you will have to wipe it down with mineral spirits or paint thinner
that will help remove that surface and let it dry for you."

Last time I used this stuff, I used some degreaser followed by a pressure cleaner, followed by brake clean and it seems to be holding up. Seems like it's about the same as they are recommending. Thought you guys would like to hear what Ospho has to say about this issue.