Thinking about this a bit, I reckon I know why this bleed occurs - it's because the lightmap is blurred to achieved smooth angular shadows, but this also affects joins in the lightmaps that don't touch the edge of the lightmap image... hence it's a problem with the lightmapper.
I would imagine to stop this happening you would only blur locally to a face within the lightmap image.
(only a guess though)
I would imagine to stop this happening you would only blur locally to a face within the lightmap image.
(only a guess though)