You know, Sebastian was maybe prepared to write off the first "thank you" when he helped Ciel get dressed and served him his morning tea as a still-sleepy induced fluke. But twice in the same day? Worse yet, twice in one hour?
Who are you and what have you done with his young "I demand and take around-the-clock 5 star servitude for granted and will kick you in the shins if you fail to deliver" master?]
...Of course, young master. [/brb visibly uncomfortable over here]