Firstly, sorry to hear your debacle. The joys of owning an old car eh?
If the metal wasn't properly prepared rust will come back, or if it wasnt cut out, just covered over, it'll re-appear. Or the panel beater may have missed a patch just starting (doubt it as they would have had to have seen it when giving it the respray)...
Not much you can do, just cut it out and weld more metal back in
Supremo Grandpa Car Owner
Cows would live a lot longer if they weren't made out of steak and leather