I got 120 also for row 14. I thought maybe cast on was wrong, but after I jimmied with row 2 I was able to use 121 stitches.
I searched around for errata also, but no luck there.
If it were me, I would try to decrease a stitch on my needles in row 13 since that's the stockinette part - if it's to be seamed, you can do it by the seaming edge. If not, find a spot that will be semi-hidden, like an underarm or a section that will be under a lapel (unless you want a "designer feature" smack in the middle of the back or wherever!).
Out of curiosity, are following rows using 120 or 121 stitches?
"The cat has too much spirit to have no heart." -- Ernest Menaul