Theoretically, the crank arms should be parallel (exactly 180 degrees from one another).

Just thinking out loud, other possibilities:

1) spindle flats are not correctly aligned to one another (manufacturing error).
2) crank arm could have slightly ovalized holes, and allowed misalignment

(Realize, a very small misalignment at the spindle is magnified at 175mm away (location of the pedal). Mathematically, arc length = (radius) (angle in radians) )