focus calibration 28p XCD

[Plancton06]

I am convinced that when I focus on a subject around 5 to 10 meters at apertures between 4 to 11. the background (at infinity) ends up clinically sharp, while the subject that is supposed to be in focus is slightly soft. This difference is minimal and only apparent when pixel peeping at 100% comparing the subject with the background, even when the distant background is at the edge of the photo.
Could it be that my lens needs some kind of focus calibration? Normally I would expect the opposite result, which would be having the perfect focus on the subject and struggle to get the distant landscape sharp. I have done many photos in different situations and apertures