If it really bothers you. it can be fixed. The whole quilt doesn't have to be taken apart. I do see that on the left side that horizontal row is a little higher than the row next to it. On the right, it's lower. Measure the small sashing strips in each row. If all measure the same, then half of the problem is solved. Remove the stitches on the left side of first sashing, from the bottom to a 1/4 above the rose print block. Using your ruler, make a mark on the back side of the sashing using the second rose print block as a guide to line it up. Continue for each square.
Do the same in reverse to other side. When sewing rows always sew one row from the top down and the next row from bottom to the top. I hope I have explained this clearly. I really like your quilt, it is very pretty.