Re-do.... the waves will be there always. Here's how I do my borders.... I lay the quilt out on the floor or table..whereever is long enough and lay my quilt border and PIN it EXACTLY to the top in the center of the quilt. Then I smooth the border over the center of the quilt until I get to the other end...and slide a mat under and rotary cut the border. After I sew both borders on...then I do the same on the sides by measuring with the border over the center of the quilt. My quilts do not wave..your's won't either. This method makes is so that you don't have measure two pieces of long fabric and get them exactly within an 8th of an inch of each other.