After the recent patents were issued, it was time to begin negotiations.
Teva has internationally advertised its commitment to birth control. It's wanting to get into generic Korlym as an add-on indication. If Teva thinks that Corcept's subsequent patent apps are likely to be issued, it might as well start negotiating while it has more leverage.
Corcept can wiggle the start date in exchange for royalties and milestones, and commit Teva to delay subsequent entrants.
I agree with the other sentiments. There's little imperative, aside from any internal organizational pressures, for either party to immediately conclude with an agreement. Then again, a standard agreement could probably be concluded almost anytime.