Help with wireframe artifacts on mesh procedural UV texturing
This looks like a side effect of bilinear filtering where it can sample texels neighbouring those that are at the edges of the used areas of the texture - the red/green boundary in your case.

One solution for this is to perform a "colour bleed" pass on the texture where for every 'empty'(Green) texel with none-empty (Red) neighbours you can output the average of all the none-empty neighbours, so what this will do is add a 1 pixel boundary to the red part of your image that matches its neighbours (In this case the average should be red) 

This is a solution to a similar problem seen with alpha blended textures with sharp edges where colour bleeding can sometimes appear at the boundaries between semi-transparent and completely transparent pixels when magnifying the image. Most modern art packages will automatically colour bleed the RGB channels when saving RGBA images for this reason.