Did Salt forget she is a sleeper agent? When she interrogated Orlov, she seemed to not know Orlov or the story that Orlov was telling, which seems like nonsense. She kissed Orlov's ring like everyday. Or did she just pretend to not know about it, or she was just "lost in character" and totally forgot about her initial objective or her past life in Russia?
No. Salt only pretended she did not know Orlov or the Russian KA program.
I am unsure why Orlov chose to have that conversation, but during it Salt kept perfect cover. She only lost that cover when the CIA determined to detain her.