Gibbs Rule no. 38: If it's your case, you're the Boss.
While stumbling over words to describe Gibbs's brief departure from NCIS, Tony refers to it as a hiatus. The two part event where Gibbs gets blown up, loses his memory, and ultimately decides to leave NCIS is called "Hiatus," which aired as the Season 3 finale.
While Ducky is summarizing the findings of his autopsy on Lt. Grady, Dinozzo notes the symptoms conform to Valley Fever. When Ducky inquires how he knows this, Dinozzo replies, "Lets just say I'm not going back to Arizona any time soon." Following the evidence, and Gibbs orders, Dinozzo travels to Arizona in the next episode.