For me the question would be how 'off' is the total??? If you're talking 1/2" or more then it's probably time to do some re-sewing. If less than that, probably some easing/stretching should make it work. Are you sashing that center medallion? If so, that will keep the blocked version intact. If not - or if not using larger pieced blocks as a border, it might get wonky down the road.