Continuity mistake: When we see young Gibbs sanding the birdhouse, the way he's holding the bird house changes between shots. It goes from being upright to on it's side. (00:35:30)
Continuity mistake: When Gibbs is looking at the photo of the Dog Tags in his basement, the way he holds the photo changes between shots. (00:19:20)
Continuity mistake: When Gibbs is talking to the chaplain about keeping daughters safe, the way he holds his coffee changes between shots. Note his grip on the cup. (00:23:00)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.