Had the same problem with a d9p I had in my UFO stash. Think I was trying to sew it too fast and stretched some out of shape. Just gave them a final press and cut them the same size. Quilt went together like a charm and lays flat. If the quilt police look it over, they will find that the strips are not all the same width. but a rider on a fast horse will not see that.
Love your fabrics.