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I thought this as well... until I tried the new mapping out and found that the lip material is slightly larger than the shape of the lip.

This is true. An earlier version had, I think, one more row of polygons than the current version.
If it's working out for you the way it is, that's great, but just like the teeth-n-gums thing, if you want something different, don't be shy to ask. :-)

I'm still wondering about the eyes though, and nobody has yet answered the question if I should overlap them so there's only one eye to texture and not two the way it is now.