Redrobes, yes it is the cloud maps. I found it happens rarely though. The clouds in Photoshop are nice and random, but when you apply the Difference Clouds filter a couple of times the mathmatics begin to show. Since it's similar to the way some fractal programs create terrain for a 3D sphere.

I've found all kinds of this in a few attempts to make the mountian ridges more uniform. Sometimes they become REALLY uniform.

It's easy enough to remark on it in the campaign design as "interesting geography". But then again I grew up near fields that had rows of limestone running across them. A geologic "uplift region" that was the layers literally turned on edge. So I tend to just wave my hand and explain it away rather than worry about it.