Ducky: I've learn't as much as I can from the dead. Time to start listening to the living. (00:34:20)
Ducky: See this fracture here?
Gibbs: Well...Yeah. You're pointing right at it. (00:16:50)
Abby: Aww, You shaved your mustache. I liked you with a little hair on your face.
Gibbs: I've still got my eyebrows. (00:08:45)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.