There was a recall at one point for the iPhone 5 for defective batteries. Wife took it to Apple and they changed the battery, or gave her new one iphone (can't remember).
Mine was a recall, as well. I returned it with two days to spare from when the recall was due to run out. It has worked GREAT ever since. I shipped it to Cupertino on a Saturday and had it back in my hands the following Tuesday. Amazing service!