Tidus may be overthinking this a tad. But it's not like Madoka realises it much. Sure, she sees that puzzled look on his face, but rather than her worrying that he's not getting it, she's more worried that maybe she said something a little bit too dumb..?

"Huh?"

Except now it's her turn to look puzzled when he instead fires off that question at her.

"Ah, wha-- N-No!" That's her initial quick reaction, though then she seems to think about it again, and it instead changes into, "I-- I mean, if you want to, that's fine, but.. um, that's.. not what I was saying, I just--"

Okay, Madoka, slow down! At least she herself seems to realise she's quickly descending into rambling territory, and so the girl sucks in a breath to steady herself again.

"I'm just saying.. Um, if you haven't really had many friends younger than you before, you at least have me.. oh, and Romeo too!" Since she does remember Tidus talking about him last time.

(And yes, it's really just Madoka genuinely being worried he may be upset over only knowing older people. This is how much she fusses over others.)