+1 to Eric's comment. The test for AF error isn't whether the Center is sharper than the Left or Right, because almost every lens will be sharper in the Center. Rather, the test is to compare PDAF (i.e. autofocusing using the viewfinder) vs. CDAF (i.e. autofocusing using live view) for the same part of the lens.

Assuming you've done the testing correctly, if you are still in the return period, I'd suggest returning it and trying to get a camera without the problem. If you're no longer in the return period and are only now noticing the problem--because you're looking for it?--then it may be something you can live with, at least until there is more evidence Nikon Canada can repair the camera.

Mike