I am doing a garter stitch, just to practice not picking up stitches and to get the hang of things. I think I am moving the yarn over when it should be under as I move the work around to start on another row, or something like that. I'll knit another row and see.
EDIT: I was right. I played with the yarn a little bit and saw how the loose stitch at the end, when the yarn is pulled over, looks like two stitches. I must have been pulling the yarn over to tighten it, instead of under and gained a stitch that way. Glad I caught this very early on instead of knitting my scarf into a semi circular shape.