"No," Tidus answers humouredly, a chuckle in the end of it. "We talked about it, back in that jungle mission! Remember? You said you wanted to! Didn't know if you were feeling any different, now it's not so late."

Because is Inigo getting cold feet over the idea? Even though he's agreeing to it, it doesn't sound very confident for all that talk before! That talk that Tidus is sure that happened- whether or not it was actually Nion debatable, but also not the important part here.