Luke: "It's you, Leia."
At that moment, Leia thinks back to the Death Star. "Holy force," she thinks. "I kissed him." Then she thinks about Hoth and that kiss...on the lips! "He's thinking about that right now!" she thinks. "Ewww! Okay, Leia, think... how can those incidents not be completely icky.... wait, I got it!"
Leia: "I've known. Somehow... I've always known."