This is an incredibly common occurance for a beginning knitter! The more you knit, the less you'll do it. And hey-- you only picked up 6 stitches-- at least you didn't do it in every stitch and end up with 40
. There are a number of possibilities of where you picked them up-- it could have been, as Mamadawn said, not taking the old stitch off and re-knitting it, or you could have picked up the yarn in-between the stitches. What kind of yarn are you using? I'm asking because some yarns have better "stitch definition" and it's easier to see what you're doing.