Hi Ken,
Not sure that I am the best answer but here is my experience.

I am curious, is the paint you used the Testor's Acrylic airbrush paint in the squarish bottles? like this? https://www.amazon.com/Testors-Airbr...airbrush+paint

If so, I had the same problem on my first paint job. It bled under the mactac vinyl masking leaving some spots like that, only worse. the base paint was the duplicolor white that I got from the auto store. Earlier in this thread I have pics showing what it came out like.

Hopefully someone else has some better explanation.

Doug