I pulled that part down from Thingiverse and looked at it with Netfabb. I rotated it to match the orientation in your first picture, but I did not mirror-reflect it - only rotated it. It does look like somehow you inadvertently mirror-reflected the part.
By the way, John Lawrence is really an amazing designer. I think he was giving us beautiful designs here while looking for a job that would use his skills, and now he has that job; he hasn't posted here in over a year. We sure miss him, and hope that his job now is really, really rewarding and satisfying.
Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick