This also happened to me - just with my Magic Mouse
I'm sure it's a common occurrence, especially when any length of time passes between uses--in my particular situation, the batteries exploded while I was moving to a new apartment and not using the mouse for approx. a month. I'm not sure if batteries will do this to any device, or if the issue is isolated to Apple accessories (maybe due to a chemical reaction between the batteries and the stainless steel. Although this happened to my mouse over a year ago, I was pretty irritated that the mouse was fully functioning one day and completely worthless the next. I didn't even try to ask if they would replace it, but now wish I would have tried. I've still got my broken mouse, and all the original packaging--the back is just busted!!! Oh well...