If it was simply the OS system affecting things you'd expect it to be the same over all the lens. looking at your pics, it appears to be on the right hand side only. For example, looking at the one of the sluice gate, the tree on the right is out of focus. The tree in the middle, which appears further away from you is sharp. I'd suspect something out of alignment slightly on one side of the lens. If you have a filter on it, take it off and try again. If it clears up, blame the filter. If you still have the issue, it needs to be looked at IMHO.