You did great. I have no advice for you because you sure don't need it, If you don't want a raw seam there, you can cut a 5/8" seam. Then sew with wrong sides together a 1/4" seam. Next, you put the right sides together and sew a 3/8" seam. The first seam will be the fold. The result is an enclosed raw edge seam. It does add a bit of bulk, but won't ever have any strings. You can, also, use seam binding on the seam to cover it. There is another thing called a French felled seam and a flat felled seam. Google them and choose your poison.