"I do too," Strange grumbles. "There's rarely any use in keeping secrets."

Said with such an annoyed tone of voice that it's pretty obvious Strange has a personal grudge against someone keeping a secret or has personal reasons why he thinks secret keeping downright sucks. "Still, short of someone casting a spell of truth, there's not much either of us can do about it."

Fun fact: Strange doesn't know if spells of truth even exist in the first place.