This just happened to me too. Just like you said it there was an IPhone device shown as last sync 4 days ago. I removed the device and changed my password but I am wonder if the problem was really fixed. I mean I am a basic subscriber and should only be able to have two devices synced at anytime and my phone and PC have been linked for as long as I can remember. So how could a third device (the unknown IPhone) sync as well???? Something doesn't add up.