First, I assume you have the latest firmware update, yes? If not, it did add some extra precision to the OVF frame lines.
But your example is well within the tolerances I would expect for what is really a fairy sloppy system. Frame lines on most any optical finder aren't totally accurate. For that matter, neither is the view through most DSLR optical finders (it's typically 94 or 96% of the final image.)