A coworker has a 2004 TJ, 60K miles, garage kept. It is a summer toy that only gets driven 3k miles a year. He noticed that it was pulling to the left so he suspected that the left brake was dragging (and it was). When he pulled the tire he found everything on that side all rusted up (rotor, caliper, and the caliper to the point that the brake was seized)...but the other 3 wheels had no rust anywhere on the brakes. So what could have caused this to happen on just one side, and to the extent that it was rusted?