OS X Mavericks scrollbars appear even without external mouse For about 2 weeks now are the scroll bars appearing permanently at my mac. I know that they appear when you have an external mouse connected. It was normal that they appeared only when I scrolled, but now they don't disappear anymore.  

MacBook Air Late 2010, OS X Mavericks 10.9.2
For what ever reason you have this enabled in your general preferences