My 2010 Silverado 1500 has developed a crack in the same area about 6 months ago. As with everybody else, not real happy about this. Truck had 36k miles on it and a little over 4 years old when it happened. Thought I was stuck with it but now I see there are some options. Would seem to me some kind of design flaw. Will contact GM first to see what they have to say. With the other design flaws they had along with the cover ups of the same and all the recalls and congressional investigations, not looking very good for consumer satisfaction and confidence for them.