Finnick's fairly certain she would have figured it out by herself given enough time, but he keeps that to himself. It's not worth arguing.

But he does slip off the bracelet on his wrist, the one Haymitch gave him prior to entering the Game, decorated in flames.

"Collateral," he says, handing it over. His lips slip into a smile then as he adds, "And name's Finnick, by the way."