Brake Disc Caliper problems of the 2002 Chevrolet S10

After I'd owned the vehicle for a little over 3 years and had only about 13,000 miles on it, it began to pull hard on braking. One of the front brake calipers seized and ruined the front rotor in the process. Although the truck was just out of warranty, because of the low mileage and age of the vehicle, I took it to the dealer. Chevrolet refused to honor the repairs under warranty or acknowledge any problems. They said it was because the truck sat outside. It is parked on a paved street in front of my house. It is a truck and most trucks in my experience "sit outside," so I found this explanation totally unsatisfactory. Whatever happened to "like a rock!" I replaced both front rotors, both front calipers (upgraded from oem) and of course the brake fluid at my expense. Again this year, in may 2012, I experienced the same problem with a front caliper seizing. I took it to the dealer again and the dealer verified the problem and said I needed to replace the calipers, pads and, in addition, the brake lines. They offered to do this for a mere $975 plus tax and $80 for new pads. I will once again replace the calipers, pads, fluids and this time the brake lines which I suspect were the original problem. When I flushed the lines to replace the fluid back in 2006 and again in 2012 there was obvious contamination in the lines which when it builds up in the caliper, in my opinion, causes it to seize. I've owned a number of vehicles most of which sat outside for years and never experienced any type of problem with the brakes. My complaint is that I believe Chevrolet used substandard lines in their vehicles or allowed contamination of these parts or designed a defective system that allows condensation to infiltrate the system and destroy the lines.