Inigo laughs a little at Tidus's expected protest. Though he doesn't seem to think what comes after - the caution - is unwarranted, since Inigo himself grows more serious for a moment too, glancing between the other two.

"Usually.. does that mean there are times when it hasn't been?"

Which isn't really Inigo angling to get all details about it. That's not important. It's more about making sure it absolutely wouldn't bother Taiki, because the last thing they need is Taiki growing weak or ill because of the content of his Arms Band.