it would be slightly different than if he had written it directly after it happened.
Explanation:
Peoples memories change everytime they remember them, based off of their emotions at the moment and new life experiences. This would change somebodies knowledge of what happened. First hand accounts are always better, because it is fresh in somebody's mind.
Katniss was thinking about what Haymitch told her. He said that she just needs to focus on running. Do not try and grab any of the weapons nearby. She was weighing the odds.