How Did I Get One Extra????

Tonight on a boring New Year's Eve, I casted on 92 st for my shawl ... did the garter for 8 rows .. row 9 was k .. then was k6, p80, k6 ... the k6 was ok, the p80 went fine till I got to the end and had SEVEN STITCHES!!! Don't know how I managed that ... I was on row 9 so I pulled my circs out because I had done a loose stitch right down near the beginning so wanted to pick them up .. five fell through the loop and I ended up taking the whole thing out .... agghhh

Toby