You're probably knitting inside out. When you're doing ribbing it's not as obvious so you probably didn't notice. It's pretty common to new knitters.
When you knit in the round you knit on the outside of the loop of knitting so when you're holding the needles to knit the circle is away from you and the needles are closest to your body. Here's a page with pictures. Scroll down and you can see how you hold the needles.
Go back to the beginning of the first row of stockinette and flip the work around so you're working on the outside. When you do that it may cause a little hole, but you can fix that later when you're weaving in ends or with a piece of yarn.