This is one of my favorite lines of the entire series. It's so flirty in Katniss' way, like when she kisses his bruise after the tribute parade.
She loves Peeta's unpredictability because it's a safe unpredictability. She expects the worst and what she always gets from him is the best. He surprises her by being completely different from anyone she has experienced. Katniss can't even imagine good things, pretty much admits that the only way it happens is in dreams on rare occasions, and here comes this boy who constantly does good things and has incredible talents. It's utterly shocking to her.
He fascinates her from the get go with the bread but continues to do so, on the train, during the parade, during training and on and on to her realization the night before during the rule change announcement and thereafter throughout the series. What she fails to realize here is she is already interested and her brain is just catching up now that she's "allowed" to care about him. Before she was in denial. That's why in the cave we start to see her catching on that things seem Real™.











