Lee's face was full of serious enthusiasm until he realized it was Kakashi who had answered his knock, and then the young Genin's expression changed and he gave Kakashi The Look. The Look clearly stated 'I don't understand this and I'm not sure I like it, since I'm wondering if you didn't seduce Gai-sensei with some impure wile, but as you are now Gai-sensei's Dearest One, I will jump in front of a kunai for you'.