I would hand stitch those oopsies closed again. Just tighten the seam up a bit, make sure you are sewing through intact material. In that a big a project it won't be very noticeable. The idea is to basically applique the top strip to the bottom strip. Then if you want to go crazy with fancy stitches on top - go for it! And remember - we all make mistakes, that's how we learn what NOT to do. Keep checking to make sure the strip on the bottom hasn't shifted while you are sewing.