The metallic fleck in the Tuxedo Black was man-made in Japan. Since the 'quake and tsunami they have ceased production of the fleck material.
I'm guessing that Ford has not been able to find a replacement for this material and has since looked into other options.
Here's a link from MotorTrend shortly after the disaster:
Pigment Problems: Supplier Issues Could Leave Ford Without Red, Black Paint - WOT on Motor Trend