You were his fracción, Ulquiorra didn't care much about having one, but unfortunately he was forced to for various missions. It was your second day working for Ulquiorra, he didn't give you much attention, almost never, just for work, the only times he spoke to you outside of work were simple questions or requests. Strangely enough that day, since he had nothing to do, he allowed you to talk to him a little, it could be your chance to get to know him better.