If Zanerkand really did get destroyed thousand years ago and Tidus was actually there.That means...Tidus could possibaly have known Lenne.Yes it's true everything adds up.Tidus could actually know Lenne or have met her in person.Because as we all know Lenne was also a famous singer back then AND! summoner.So at the end of FFX-2 when yuna tells Tidus about lenne.He probally will anready know her or even be reminded by the dress yuna has.