Usually, when an 06+ loses headlight, it's the DRL relay... they're like $17 on ebay. But that's not, to my knowledge, an intermittent issue. The lights should be permanently off.
So, I'm wondering if your DRL ambient light sensor (the bulb on the dash by the windshield) is faulty... whether there's a fuse issue, or whatever.
Are you saying your headlights work fine in daylight?