I seem to be haveing a problem with one of my parts.  I bet its real easy to figure out becuase ive been working on it for 2 days now.  The part is a die cast heat sink with a couple mounting holes.  The mounting holes are perpendicular to the mounting surface which is drafted at 1°.  The mounting holes were created by a sketch with the centers coincident with the mating parts mounting holes.  The mated part was imported from our customer.  The mating parts holes measure 72.50000mm apart along dZ.  When i measure my part in the asesmbly, the mounting holes are 72.50000mm along dZ.  When i open the part and create a drawing, the mounting holes are now 72.454mm along dZ.  Likewise, when i measure the holes in the part file, they are 72.454mm along dZ.  Going back to the assembly, they are 72.50000.  The mounting surface measures 1° off from the right plane and top plane (drafted surface) and perpendicular to the front. 

Any ideas at what im doing wrong?