Many people can pick up on that situation, during or after.
Depends how you phrase it.
"Jessica is the reason we hired you - she says you'll be great here and when she says that she's always right" technically says "we weren't going to hire you", but also "we all believe in you".
I don't think it would make sense to tell a hired person "you barely got in here, everybody hated you except for one interviewer".