There are a lot more intelligent things Madoka could say to that. Maybe share some more insight on the mission, or saying that she'll take care of everyone on the blue team as well as she can - which she is intending on doing!

But no, instead she's just distracted by that last thing Tidus says.

".. big Pi?"

Apparently this girl isn't well-versed enough in the world of nicknames to immediately realise what Tidus means..