How we cite our quotes:
All I was doing was trying to keep Peeta and myself alive. Any act of rebellion was purely coincidental. But when the Capitol decrees that only one tribute can live and you have the audacity to challenge it, I guess that's a rebellion in itself. My only defense was pretending that I was driven insane by a passionate love for Peeta. So we were both allowed to live. (2.4)
Katniss didn't realize the ramifications of her actions during her first Hunger Games. She just wanted to "keep Peeta and [her]self alive." That was as far ahead as she could see. But what she didn't realize was that by saving herself and Peeta, she made it seem as though she was a rebel working against the Capitol. And inciting a rebellion is the best way to piss off the Capitol.
"In several of [the districts], people viewed your little trick with the berries as an act of defiance, not an act of love. And if a girl from District Twelve of all places can defy the Capitol and walk away unharmed, what is to stop them from doing the same?" he says. "What is to prevent, say, an uprising?" (2.19)
Here Katniss begins to realize what she's started, as Snow warns her that her actions, made in an innocent attempt to survive the Games, have far-reaching consequences. Instead of getting to retreat into obscurity, she may have inspired other people to start rebelling too. If so, the implication from Snow is that she'll have a heavy price to pay.
"What about the other families, Katniss? The ones who can't run away? Don't you see? It can't be about just saving us anymore. Not if the rebellion's begun!" Gale shakes his head, not hiding his disgust with me. "You could do so much." He throws Cinna's gloves at my feet. "I changed my mind. I don't want anything they made in the Capitol." And he's gone. (7.80)
It's Gale who helps Katniss realize that this problem is bigger than she is, and the solution has to be bigger than her small idea of running away. This isn't just a matter of getting small groups of people out from under the Capitol's dictatorship. It's about getting everyone out. "The rebellion's begun," which means that a full-scale war is on the horizon.