Ridiculous moment of Find the Seam. I love this little assembly job! We do not often see single row stripes. They take a little extra work when knitted flat, as you need skeins at each end, but how sweet is this?!
A couple of my finishing tips, especially for baby and kid knits - I always bind off the stitches where they tell you to pop them on a holder for three needle bind offs or using in the neckline later. If something happens to the seam or neckline those stitches are vulnerable to dropping all the way to the cast on. One of my learn the hard way lessons. In a slippery ribbon no less. For this seam I bound off each shoulder in green, then worked the seam in white. You do not have to pull the seam any tighter than the knitting, again because the bind off is secure. This way the seam looks like you kept knitting, not like it was thrown under a sewing machine.
You have probably spotted it, the fourth row of white above my thumb, the row that is littler looser looking, above the one with the split green/white stitch.
Okay, back to work!