[ This person seems very focused on their being a secret passageway. There's a small part of her that hopes they're right, it would be a little exciting if it were true. But it's also a bit terrifying, not knowing such a thing; if she were home then it's almost certain she would know, though wizards have their mysterious ways. ]

A mechanical trigger seems the least likely to me. Anyone with enough dedication could find such a thing. Wizards are most likely to have a spell with a key that would trigger a hidden passageway, though I would believe finding such a thing we are not meant to find would be a violation of some rule.