Yes, the artifact IS where the seam is.  What's confusing is the 'way' that I moved the seam... since it's a tilable mapping (ie. used the full extents of the U space from 0.0 -> 1.0 ) and the bitmap being used is also tilable, to move the seam, I just grabbed the uv-polys starting at just right of center and dragged them to the left side (into the negative UV space) and re-attached (stitched) original seam (which would now be at 0.0 on the U axis) .

See the attached image (to help see the selected polygons, I added a dark overlay where they are).  The texture fills the 0 -> 1 UV space entirely.

The uv-polys hanging off to the left (in negative U space) will get 1.0 added to thier values, essentially moving them back to where they were originally on top of the texture, so it renders "seamlessly", but there is still a seam there on the U axis.

Does that make sense?

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