could be a caliper that is binding when it is cold. When it heats up, the brake fluid thins and lubricates the moving parts and the metal parts (caliper body?) expands, freeing up the mechanism...
Well thats my theory. See if it comes under warranty.
XF died, Now It's a 6-cyl Cortina!
Rear ended 3 times, 4 close calls.
All while I was stationary, still counting the idiots..