For your information... Microsoft don't ask of any proof of issues with a Surface that's under warranty. I got mine exchanged and there wasn't anything wrong with it (I didn't know that at the time though) still, I was glad overall because I managed to scratch the casing on my original one!
I ordered a refurbished Surface Pro 2 64GB i5 unit with type cover from the Microsoft store and they ran out of stock. So they sent me a refurb Surface Pro 3 i5 128GB with type cover instead. Free upgrade. I was stoked! Love my SP3.