Apple explained this already. They have high resolution / high speed cameras analyzing each phone as it goes down the assembly line and automatically selecting the 'best' bezel out of something like 64 possible bins.
the one on the left is much nicer, but seeing as the device has been out for such a short period of time, can we tell which device was actually manufactured first?<p>Or is this a case of different suppliers having slightly different parts? which seems unlikely for a new Apple product, but the one with the gap between the aluminium and glass seems all kinds of wrong anyway.