My First Sleeve.......Dec. Question

[Arielluria]

I'm making this Textured Cotton Chenille Sweatshirt and this is my first sleeve ever.........I need to ask a question........

The pattern reads:

SLEEVES: Work from sleeve top to cuff. With larger size single point needles cast on 69(77,77)sts. [Or see Sleeve Note at bottom of pattern for knitting sleeves directly on sweater body.]

Row 1: RS: Purl
Row 2: K1, *p3 tog, (kpk), rep from * until 4 sts rem, p3 tog, k1.
Row 3,5,7,9: Purl.
Row 4: K1, *(kpk), p3 tog, rep from* until 2 sts rem, (kpk),k1.
Row 6: Repeat row 2.
Row 8: K2 tog, *p3 tog, (kpk), rep from * until 5 sts rem, p3 tog, k2 tog. (place marker to note decrease row). [Note: It is easier to keep track if you do all dec's on a purl row.]
Row 10: K1, *(kpk), p3 tog, rep from * to end. Continue in pattern as for rows 1 -4, at the same time, dec (as in row 8) every 6th row until 31 sts rem. Work until sleeve measures 16.75 (18.25,18.25)".

But the first decrease ("Row 8" above) was NOT on a purl row!