Not a problem of the scenery, which is probably why you haven't see it reported, it looks more like a video driver problem (maybe a wrong tweak that was applied), that has issues with fog rendering.
It might be visible on KDFW only, because such problems are related to the size of the ground polygons sections, and KDFW has (by far) the largest of all so, other sceneries might not have sections large enough for the problem to appear.
If the issue disappear if you enable unlimited visibility, then it's sure a video driver issue related to fog. If not, then maybe it's something else.