Yesterday, Sallie told the other housemates her suspicions that something was up
"There are conspiracies in everything people!" she told the group earlier in the day. "People are out to manipulate people.
"How do we know everyone in here is a real housemate, how do we know someone isn't a mole?"
Confronting Michael in the bedroom, Sallie questioned him on his story as a postie.
"I feel like there's something you're not telling me," she pushed, as Michael looked pressured.
Sallie - dubbed "Sherlock Sallie" by the others - continued: "Are you a... ? I just think something's up."
Michael got wound up by Sallie's questions, telling her: "You're stressing me out!"
But an unconcerned Sallie continued to discuss the issue with her fellow housemates, before Michael decided to retreat to the bedroom.
Later he apologised: "I'm sorry if I snapped at you earlier. I'm just tired and hungry."
Michael then signed as he lay in bed alone: "The game is started."
Big Brother airs nightly on Channel 5.