I was free motion quilting a small quilt as practice and when all done and so proud of myself, discovered that the Supreme Slider had somehow got "loose" and I had quilted a large portion of it to the back of my quilt. Had to pick it out and have never used that slider again. It was supposed to make the bed of the machine slippery and make sliding quilt around easier.
Still don't understand why I did hear something or feel something was wrong.