Did you measure each border before attaching it?? I wish you had posted a photo. If the ripple is in the first border on just one side, I would just carefully take the borders off on that side. You will have to be so careful when reattaching them in the same order.
The other suggestion might be to remove the border side as a whole, then pressing it carefully with some starch and then start to measure each border and see how much larger it might be to the size it should be. Sometimes when doing multiple border, it is easier to sew them together and the miter the corners.
Good Luck
