Lighter colored shorts hold up better than dark shirts,

I love the overall service from Sticker Mule, orders are processed quickly and the support team responds to inquiries and works hard to correct any issues. My first few black T shirts from them came out great, but lately, black and dark-colored shirts come with some sort of residue on the shirt. I am told it is a some sort of non-stick coating, which I understand, but it is visible on the shirt front, and changes the texture of the fabric. Washing the T shirt inside out as suggested, and the residue does not wash away after 3 wash/wear cycles. After the third washing this texture is softer, but the fabric is now wrinkled, so it looks a bit worn until it stretches back out. Interestingly, the same print on the grey shirts, seems to hold up much better, and do not have any of the issues with the dark shirts... Not sure how many more grey shirts I can add to my wardrobe. Would reorder on the grey T short, but not on black/dark blue.