I haven't knit that sweater, but I get what you get math-wise. That's funny that she doesn't tell you how to deal with the extra two sts.
I think what I would do is rip back and decrease two sts in the last round before the ribbing.
Can't wait to see it when it's finished!
ETA: I see that Ingrid beat me to it, but I'm very pleased that I came up with the same solution she did!