It was probably a defect in the powdercoat. If they didn't get good adhesion to the metal or use a corrosion protectant like a phosphate dip then you could have issues. Especialy if any oil was spilled by the owner and penetrated the powder somehow.
I have an 07 Night Train and at only 79 miles the front wheel hub had the chrome peeling, and also the lower legs had what seemed to be corrosion on them. Also the powdercoat was bubbling around the front and rear master cylinders. I went to the dealer to see if it was covered under warranty and they said no, its because I didn't wash it.... LOL, really? Must have gotten really dirty in that 79 miles. I am figuring they really cut corners on quality sometime around 07, slowly re-powder coating there mistakes.....