Why does Amir ask Baba if he had seen the new watch?

The next morning, Amir hid his wristwatch and a bundle of cash under Hassan's bed. Then he told Baba that Hassan had stolen from him. Baba called a meeting with Ali and Hassan in his office. When they arrived, their eyes were red from crying. Hassan lied and said that he had stolen Amir's wristwatch and money. Amir felt a pang of guilt because he understood that Hassan was sacrificing himself for him as usual.