Under Covers - S3-E8
Continuity mistake: When Jenny joins Gibbs and Fornell in MTAC, she puts on a headset and lowers the microphone. In the next shot, she secures the headset and lowers the microphone a second time. (00:28:45)
Continuity mistake: When Gibbs is outside Jenny's house and calls her land line, the folder on her lap is closed, then open, then closed again, without her touching it. (00:23:55)
Continuity mistake: When Abby and Gibbs determine that the ambulance exploding wasn't an accident, McGee is visible next to Gibbs. He then mysteriously disappears, and a moment later, walks around the ambulance carrying an evidence baggy. (00:08:15)
Chosen answer: It is never stated, however she must have been there several years if she is on presidential detail.