A good cleaer picture would help us see the stitches and identify it.
Gaining stitches happens - if it's knit and purl sts on the same row, you may be taking the yarn over the needle instead of between the stitches some of the time to switch from yarn in front to yarn in back. It can also happen at the beginning of the row if you put the yarn to the back over the needle which pulls up the first stitch and each leg of it looks like a separate stitch. Hold the yarn out to the side a little and then you can see the first stitch more clearly. Of if there's incs and decs in it, you may have done an extra inc or skipped a decrease on a few rows.
sue- knitting heretic