Once he's gotten into the bullpen, Gibbs's mood goes sour when he sees Jenny sitting at his desk, holding a cup of coffee which means that she's been pressing his team, his own people for information in regards to the annoymous John Doe and the possibility that Lance Corporal William Danforth Jr might have faked his own death.
He hates it when she does this to him.
Unsurprisingly, she did this before when she was just a few days into her new role as the NCIS Director when she decided to add Ziva to his team without ever consulting him or even asking for his opinion on the matter. Although Gibbs has forgiven her, he still gets pissed off with her at times.
It's like she doesn't trust the team to do their jobs properly and so she insists on butting in at any given opportunity.
It's very annoying.
Luckily, though, Gibbs has a plan up his sleeve.
Since she's at his desk, he's going to sit at hers and set an example, his point being that she doesn't go behind Gibbs's back and expect to get off easily just because she's the Director. Hopefully she'll take the hint and leave them alone to do their damn jobs in peace.
If not, then Gibbs is going to have put a repeat performance again but that he doesn't mean he isn't going to enjoy pissing Jenny for doing so.
He has a reputation as a bastard to uphold, after all.