Is this a common paint problem?

I had a scary experience this winter - the paint on my rear bumper started to flake. It started on the edge of my bumper just behind the rear wheel. Same thing on the side skirt just behind the front wheel. The problem was properly caused by show, roadsalt and rubble from the tires.

BMW was nice about it. They offered to repaint the bumper and side skirts, but I ended up getting a good deal on the M-Sportpacket II instead.

I now have my newly painted bumpers and skirts on, but I'm a bit nervous about this happening again. Have any of you experienced similar, or was I just unluckey with the factory paintjob on the bumper and skirts.

JSE