They do use water-based paints, the sales guy told me it was because the EPA is making everyone do it. I had the same kind of thing happen, I hadn't got a chip in my old car for 3 years, then got one the first 2 months that i've had my 330xi. I haven't had one since, but I stay pretty far back from other cars now as a precaution. Not much that we can do, cept maybe get a bra.
Titsilver metallic 2004 330 Xi 6speed manual