I wouldn't take anything apart but just set a second line of stitching next to the original on 4 of the centerpieces and see how that looks. Maybe start an inch from the last circle?
If you are the cautious type use a long long stitch and odd colored thread. Don't like it, pull the odd threads out.
If you do like it still pull the odd threads out and sew you second line of stitching corectly with the right thread.