Lines show up when tiling images on iPhone simulator

I've got an actor that is wide, and has an image that tiles horizontally. It looks fine on the preview in GS, but when I load it into the iPhone Simulator (I don't have a Apple license, so can't test on real device), lines randomly show up where the image is tiled. Anyone else have this problem or have a solution?
Comments
Ok, would a screenshot be helpful at all? It's basically just a 1 pixel blackish line that flickers when the scene scrolls. Sometimes it stays, sometimes it doesn't. I've never had it before, and can't find anything on it.
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Thanks