Yup, the trigger is the distance to the plane.
The problem happens in non-photogrammetry areas ; it is a LOD (level of detail) issue where the LOD0 (highest quality, for stuff close to the plane) textures do not originate from the same images than the other LODs. Which may be ok for a map site like Bing Maps (having colors / seasons shift when you zoom in) but is of course unacceptable in a flight sim.