Yesterday I received an Ex+ copy in Copal 0 shutter from KEH. The aperture scale goes from f/5.6 to f/32, but I can move the aperture selector further left or right of the scale. What surprised me is that, when I select the "maximum aperture" of f/5.6, the diaphragm closes a bit, so the real maximum aperture with diaphragm fully open is some unknown value greater than f/5.6. Is this normal for this lens, or is my copy defective in its apertures? What I mean is, that maybe my diaphragm is misadjusted and f/5.6 should have the diaphragm fully open.

Thanks!