That was just a general chat. I was thinking of a specific talk between Tybalt and Jill on the Sunday after Hell Week ended. Jill mentions it over breakfast (though she doesn't say what it was about). I thought she brought it up again, but I can't find that anywhere (beyond a reference on the phone) so I have to assume I imagined it.
I must still disagree with
Roelandt though; it's an odd thing to have Jill mention if it's never going to come up again. If the goal was to explain why the MC didn't spend the day with Jill, she could just as easily say she wants to head back to the mansion to make sure nothing in her room was damaged. The fact she specifically mentions meeting Tybalt suggests we're eventually going to either see that meeting, or learn the results of it. Doesn't mean it will be anything earth-shattering, just that it will come up and thus we see the groundwork laid here.