Commatoze

Late last fall, I installed a pair of PIAA 1500XT fog lights to replace the OEM's that were removed when my bumper was installed. This week I was surprised to see that the mounting frames, and sttaching screws were rusting, and corroding badly from the winter salt baths. I've never known PIAA's to rust. I have a pair of PIAA 520 driving lights that are exposed to the same salt spray and a pair of PIAA 40's in the rear bumper that get plastered with salt, and they show no signs of rusting. I bought the fogs as "new in box" at an online auction, from a commercial seller. Is it possible that these are knockoffs of the real thing? Anybody else have rusty PIAA's?