If I'm seeing what you are seeing... and it may be an idea if you were to crop just one bit of vertical striping and post that so we know we are talking about the same thing... I would try a couple of things 1st.
We can't be sure what is causing it until we do the elimination thing. Take photos of basic neutral background, and duplicate the f/stop and shutter speed for this one. Do this with the background in and out of focus. Now, change the aperture and do the same thing. Now change the shutter speed and do the same thing. This will help to narrow it down to whether it's a focus thing, or a shutter thing. The aperture won't directly create stripes - but the degree of DoF it imparts may have an effect.
The thing is that it may be a RAW conversion thing. If you still have the RAW file (pre Aperture import) download Lightroom (30 day trial) and see if the artifacts appear there. If not, then it may be a RAW conversion algorithm thing.... recall that a RAW converter is demosaicing the sensor data. Or something like that.... I don't quite understand that one myself. But running it through a different RAW engine may produce different results.
Good Luck.
