It does look like an inadvertant yarn over when you switched from knit to purl (or purl to knit). If the extra yarn is only what is shown in your photo, I agree with Sue, just ignore it and go on. When you've knit a few more rows you can pull this area sideways and lengthwise to work in the extra yarn.
If you're in the middle of tinking and you want to continue doing that, here's a video that may make it easier.
For purl sts, you do the same thing but pull the working yarn up from the front rather than the back.