In "The Tsuranga Conundrum," when Yaz locates the bomb on board the ship they're on:
DOCTOR: Ten points for Yasmin Khan. And yes, I am keeping score, for all of you. Ronan, up your game. Jokes. So...
Then, in "Demons of the Punjab":
PREM: What's she saying? RYAN: If I had to guess, I think we're going demon hunting. DOCTOR: Gold star for Ryan. Oh, wait. Was I awarding points? Oh, I forgot about the points.
Source: chakoteya.net