It is the texture filtering. A filtered texture is basically blurred which means every pixel gets some info from nearby pixels. However, the actual areas on a figure that wrap around in 3d space are not near each other in UV space. Thus the pixels just outside the actually used part of the image are contributing to the color.  As 4blueeyes said, a well done texture image includes data outside the boundaries of the used part of the image that corresponds with a completely different area, or at least is similar, thus minimizing the discontinuity.

Turning off texture filtering should fix it. It is nice that P7 introduced control for this on each material instead of the whole scene, but it was really stupid of them to enable filtering by default.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)