iPhone replacement unlock
So today I went to the Apple Store to get a replacement iPhone 5 because my original one was shutting down unexpectedly. However, once I got the new one I restored to try to get the "Congratulations, your device has been unlocked" screen but I never did. I bought the original device from an Apple Store at full price and it was unlocked from day 1. I don't understand why this device would be locked to AT&T if it's just a replacement of my previous phone, if I already had the unlock why would AT&T lock a replacement?
I have contacted Apple and they said they can't do anything, I contacted AT&T and they said that they're not sure whether I will be granted an unlock given that I used the phone on goPhone for a few weeks. I filled in the AT&T unlock request form anyways and I hope that that works but if not I need to know what I should do? Should I go back to the Apple Store and tell the genius to give me my original phone back? Is it a problem on their end?
iPhone 5, iOS 7.0.3