All the edges of your braids would have been bias, bias stretches. (I am assuming the braid pieces were rectangles that you trimmed straight before sashing?) if that is the case, sew the sashing on by drawing a straight line and then trim off the extra.
Besides the bias stretching, I always stay stitch the edges of my top if it has a lot of seams because every seam stretches a little. I mark my borders or sashing where the end should be, pin down the edge distributing fullness and ease the top to fit with my stiletto.