I think charsue is right. It's kind of like needle and thread. I always wondered why my thread would twist so badly that I would need to let the needle hang so the thread would untwist. I found that I give a slight twist to the needle when I pull it through the fabric, which then twists the thread. I am working on correcting this, but it's harder to unlearn something. Maybe it is as simple as the way you are setting down your iron after you use it.