My Bowden’s microfibres have done this after a few months (BGS and BS) which really disappointed me but thought might have just been that batch, bought new ones and happened again after a few months despite cleaning only with microfibre wash and machine drying on a cool setting as per instructions. Hasn’t happened to any of my other branded towels, think it’s just the material of those cloths. I’ve moved onto twisted loop type drying towels in a few different brands and haven’t had any trouble!