That isn't very wavy. I am wondering if you are stretching your binding while applying it. That could be causing this little tiny bit of wave. Here is a good blog posting about possible causes of wavy borders.
http://www.apqs.com/blog/2013/06/11/...-wavy-borders/
Large waves are caused by not measuring the border fabric before attaching but simply taking a large strip of fabric sewing it on and cutting.