A swing and a miss

While checking the bityExpress-C board that I assembled, I found that most of the power rails were shorted to ground.  I inspected the PCB before assembly, but I did not check for power shorts.  After finding the shorts on the assembled board I checked my two remaining un-populated PCBs and found the same shorts.

I re-ran the DRC in Altium (my EDA tool) and it passes.  I opened a service ticket at OSH Park.  If this does turn out to be another error by OSH Park I may have to find another PCB house.