The slipknot can either be a purl or knit stitch, I looked at it closely and there is a purl bump and a V (a small reminder that knits and purls are the same but reversed). It'd be easy to switch it based on your pattern because you can just take it off flip it and put it back, although it won't make a big difference since it's one stitch among an edge, which is bound to look different than the rest of the work, and it's one stitch of hundreds(for most things). 

The bottom line is if you look closely you can tell whether or not it's a purl or knit(it can differ based on your slipknot tying technique) and you can choose which one you want.