This excerpt from the Tire Rack seems to explain:
"As tires are cured, a release lubricant is applied to prevent them from sticking in their mold. Some of the lubricant stays on the surface of your tires, reducing traction until it is worn away. Five hundred miles of easy acceleration, cornering and braking will allow the mold release lubricant to wear off"
...But there is nothing on the BFG site about it or any tire break in.
BTW... nice looking tire.