I sold an iMac a couple of months ago, and just noticed that there's an iMac on my Devices list in Find My iPhone. The iMac isn't named (my name)'s iMac, but named (someone else's name)'s iMac. I erased my iMac and installed Snow Leopard on it prior to shipping it. So why does it keep showing up in my Devices list? I removed it from my account, but it reappeared. How is that possible? And how do I remove it permanently?