Fuck me, that must of been heart breaking to sand that new paint!
The lad who sprays my cars mentioned he has major problems with silcone in the air, causing this type of thing. Even cars pulling up at his workshop with a fresh coat of back to black bumper cleaner or dash shine stuff!
Hence why the big players have spray booths.
Just thought I would mention, dont know why really as I know fuck all about painting cars!