Concerning the You Tube video on May 10 in which Jenny from Missouri Star Quilt Co. made a minkee rag baby quilt: the backing was flannel and the front was minkee charm squares. Should the flannel backing be prewashed because flannel shrinks so much? The charm squares wouldn't be prewashed I assume. But I am worried about the flannel shrinking once the quilt is washed. Any thoughts anyone? TIA