Are you adding a p1 to round four? It looks like it's staggered one stitch off from round two. In the pattern on about.com, you have...
Rows 1 and 3: (right side) Knit.
Row 2: Knit 1, *slip 1 with yarn in back, knit 1. Repeat from * across.
Row 4: Knit 2, *slip 1 with yarn in back, knit 1. Repeat from * across, ending with an additional knit 1.
Row four starts with a k2 and ends with a k1, while row two starts with a k1 and ends with the repeated pattern.