I suspect that the terms and conditions didn't start getting thrashed out until Sweden made the formal request. At this level of play there is usually a lot of red tape to work through as two legal systems collide. Which is why you don't leave it to the last minute.

(While I admire the work WikiLeaks has done, I find Assange to be an egotistical idiot but given the number of unusual events that have occurred during this whole affair one can't help being interested.)