I had a long day yesterday and when I posted...it was late...for me. I just reread your original post, what grit of sand paper did you use under the sealer and primer...How long of a flash time did you allow between coats of primer and sealer. You mentioned you needed to repaint a fender and door...why? Was there body damage? Did you use filler? How was the filler applied and over what? What grit of paper did you finish the filler in (if you used filler) before you applied primer?
I'm rereading your post and a step by step analysis of what you exactly did would help. Not only the proper way to repair the area but, if an error was made, so that we can correct it for you and explain what happened.