Tragedy strikes

After only having had my NEW quilt on my bed for one week, I popped it in the washing machine (delicate setting, as I do all my other quilts) and all the vertical machine stitching came undone.  After wondering and considering most everything that could cause this, I realized that I recently organized my threads and remembered finding a bobbin in the thread box with slightly glimmering thread.  Still wondered where and what I used this for.  Now I realize I put it there for a reason............ it was wash-away thread and when I re-organized the threads I must have moved it to the bobbin holder.  In future I will definitely label the bobbin..... what a bad way to learn a lesson!!