I have a contract with AT&T but I can upgrade my phone for a discounted price. When I go look at the options online, it seems I can only choose a non-refurb iPhone 4 (or both new and refurb 3GS). But if I go to the AT&T store page, I see they're selling iPhone 4 refurbs to new customers. What gives? Temporary glitch in the system, or at they not making that option available to current customers?