I might be wrong but it looks as if there is some puckering and "waving". The wavy lines normally comes from not measuring your borders right. If you just sew them on to each side instead of making them all the same size and easing the fabric in if needed for the difference you'll get the wavy thing going on. You need to measure your borders and it both sides should be the same (average them) and then measure the top end after you put the sides on and make sure the top and bottom borders are the same as well. I'm sorry if this isn't the case it may just be the way your quilt is layed out.