I noticed earlier with some (many) of my screenshots that they seem to have a frame, as if the actual game is not entirely straight (starting at 1,1 instead of 0,0). The menu appears to be simply shifted by (1,1), but while playing, it's often fading by the top right, as if there is a small rotation. Today I realized the frame is also visible in the menu. Even here on the forums you can see on the left hand side, there seems to be a slight border, most visible at the middle with the white sky / fog / cloud. It's clearly not always there, so something causes it to appear, or disappear. Of course a small thing but if it's trivial, might be worth a look at. ps.: I only found one such streak of shots from recently, and it has 3D weather. Might be that. And of course a problem with the wallpaper image itself. (Well, not a problem. Thing. Said problem first because of the artifact.) Even better visible on this one:
