Perhaps the interaction of ammonia residue in your T-shirt/towel mixed badly with the conditioner. FYI: ammonia is one of the strongest, most damaging respiratory irritants. Waaay more damaging to your lung & sinus tissue than mildew could ever be. I don't even allow it in my house. The fumes from leftover residue in textiles is enough to give me an asthma attack. If you really like using it, I'd consider at least setting your washer to the extra rinse cycle. But borax does the same thing, & is safe for skin, kids, your drains, & the waterways.