I'm not so sure about it being from Europe. Maybe someone waiting for someone arriving from somewhere in Europe?
As I'm in Europe now, with the strength of the Euro against the weak dollar, it seems crazy to buy an iPhone here, on my way to the US.
I'd say checking with Apple to see if you can get info about the purchaser (although they're probably not even allowed to give out these details) or else simply at the airport... when you lose something, you always track down the place you think you left the item 🙂