Hairline gaps / seams in exported masks

I've been exporting a lot of masks from painter for use in game engines (for decals, skin colors etc) and I've been noticing the exported mask files have hairline gaps along the seams. I can fix this manually by opening the black & white mask file in photoshop and doing color range selection on the white areas, then expanding the selecting by 2 pixels and filling with white. However there has to be a way to fix this coming out of painter right? Any tips to a setting I'm missing would be awesome thank you.