It looks like you're on the highest JPEG quality, I wonder if the highest RAW quality will have any difference.

So going along with what Am said, is the photo you attached straight out from the camera?
I'm wondering if you might have had the ISO too high by accident (unless the camera does it automatically), or if noise reduction is on too high (it's generally better to just have it off, or the lowest setting if there's no off like Sony's cameras, and then post process to remove the noise).
Also, when you save the image after any editing that you may do, are you saving it at the highest quality?

My only other guess could be that maybe the focus was at infinity? I know infinity is used sometimes depending on the photos you're taking, I just wonder if sometimes it may have negative effects on the result image.