Went to our local Apple Store in Rockaway NJ to upgrade my wife's 5S to an SE Rose Gold 64 GB. No dice. Not available. Checked the online Apple Store and all the NYC stores are showing also NA. Any idea what the hangup is? Is it simply that popular that demand is stripping supply? We're not rushed so it isn't a major disruption but I'd like to take advantage of the trade in option which can only be done in person at a Store.