I would take the stitching out between the saddle block & floral frame, but not the whole thing. I would start half way down the sides & the whole bottom. Pin to the new position and re stitch. If you can't get all the way to the 2 lower corners without it bunching, leave them a bit open & hand stitch. If the seam on the left side winds up being a bit to skimpy, then take a piece of light weight fusible interfacing & iron it on the back over the seam. You want at least 1/2" on both sides of the seam, so it should be at least 1" wide. This is how you would fix a seam that has come loose after laundering your finished quilt.