I have tried your suggestions of testing both the thread and some backing fabric in water. No dye was evident from either. I then laid them on a piece of old white sheeting to dry. No dye transfer there either. Since this was all hand quilted and I am sure I prewashed both backing and top fabric I'm not sure how this dye transfer happened. I used the maroon backing fabric as the binding and saw no color transfer to the front when it was washed.So, I am completely baffled. Thank goodness for color catchers. And thank you for all your ideas.