The whole 'no carbs after xpm' thing is a myth (sometimes it is 3pm.. sometimes 5pm.... sometimes 6pm... That should say enough about the legitimacy of the 'rule'!).
The concept was originally developed to help restrict peoples night-times snacking habits (popcorn and chips in front of the evening TV) which can results in a whole heap of 'mindless' calories!
Well, because decreasing overall daily calorie intake helped the weight loss - people assumed that the weight loss was the magical effects of not "eating carbs at night"! So the myth has stuck.
Generally, I suggest people focus most of their carbs around when they are most active - which for most is earlier in the day and around workouts. So if you are active later in the day then there is no reason to avoid carbs and if you workout later in the evening then carbs are pretty essential to help with performance and recovery.
But some people will also do best on diets where they space their carbs, protein and fats evenly over the course of the day (esp. for those people who have blood glucose instability issues) so they are also fine with carbs later in the evening.
And although some people argue that 'insulin sensitivity is decreased at night' the level of decrease is basically insignificant - and if you are eating healthy foods and you need the carbs/energy then your body is not just going to store it all away!
There have also been studies to show that when given a large meal before bed, those on a calorie restricted diet actually lost less lean body mass than those who ate a small evening meal.
If your overall daily calorie intake is on track, if you are getting enough protein and essential fats and if your food choices are 98% healthy, then carbs at night is not going to prove a problem at all.