Embarrassing as it was to be caught in the midst of his difficulties with the tea, the Doctor was glad of Leela and K-9's arrival. It gave him something concrete to worry about, and K-9 offered him the perfect scapegoat to vent some of his worry in the form of temper. "I know perfectly well how to make tea. I forgot how cheeky your model is." The newer K-9 given to Sarah Jane was more polite, wasn't it? The Doctor thought so, and just at that moment, he wouldn't let anyone convince him otherwise, regardless of what the truth might be.
"Hello, Leela," he added, tone noticeably more polite when he addressed her. "Sorry. I'll have the tea ready in just a mo. Why don't you have a seat? Would you like anything to eat? We should have biscuits around her somewhere, or I could make toast, or maybe you'd like a banana. I think I'll have one. A banana, that is. I'm feeling a bit peckish, and bananas go with everything."