If your workout happens to fall late at night, your PWO nutrition shouldn't be any different than normal. Your body is still in a sensitive state such that it will absorb nutrients more efficiently and more inclined to shuttle carbohydrates into glycogen stores. Obviously, I wouldn't binge per se, but having a small carb snack PWO followed by a wholesome meal before you go to bed would not hinder your progress and would not automatically convert to fat. Again, like has already been said, focus on your total macros at the end of the day and don't be as concerned with individual meals.