How to get rid of seams from trim sheet?

[franman007]

I did a trim-sheet (still in progress) in Painter using masks for different walls, ceilings and floors. I used a lot of polygon segments on that particular trim in the form of a grid so I can easily select sections to mask. Anyways the problem now I'm facing is that when I export the tillable textures onto a planar mesh I get a thin seam as you can see in the middle of this picture. So far I've tried exporting with all kinds of dilation (setting at 256 pixels max) in 8 bit png format or 8 bit + dithering and I still see this line.. Is there another way to get rid of it?