Went through three phones. My first one had the rattle when facedown (and other problems so I exchanged it, second one had it when it was faceup and this was a green dot model (everything was perfect except the water damage indicator had been tripped not by me, and the power button was a bit loose on this one, but that water indicator was the big one for me for future warranty purposes if need be), and my third one has it all the time, but it isn't as strong and doesn't seem to be getting worse after a couple days like the first two were. If anything it just starts out rattling, then it goes away, but the vibrate is so strong that this thing would not be silent at all really. I tested my mom's iPhone 4S and it has a slight rattle as well, as well as my old HTC Fuze. As others have noted, I guess other phones have this as well due to the auto focus lens, just on the Lumia I noticed it is a lot more pronounced.