Quote 1
"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.
Quote 2
"I have a problem, Miss Everdeen," says President Snow. "A problem that began the moment you pulled out those poisonous berries in the arena."
That was the moment when I guessed that if the Gamemakers had to choose between watching Peeta and me commit suicide – which would mean having no victor – and letting us both live, they would take the latter. (2.13-14)
Katniss is good at short-term strategy. She's fast, too – she thinks on her feet. At the climax of the last book, she came up with this plan on the spot to save both her life and Peeta's, and it worked. But she's a warrior, not a politician. She was so focused on saving their lives in the arena that she didn't think ahead to what problems they might face once they got out.