Oh, and I think if the number of stitches in the placket correspond to the rows in the sweater, then you're probably right.
Could those 5 extra stitches be intended for the collar? I just finished a baby jacket that had 5 extra stitches at the end of the neck edging that were meant to be knitted into a 3 inch strip that was then sewn to the back of the neck and attached to the other side of the front, to continue the edging. I can't imagine how your stitches would be used (that's 10 stitches all together that aren't accounted for), but do the collar instructions refer to them in any way?
Hesira