That's usually a strategy used with the argument that "You want to encourage people to call when you have the position, so you bet small, giving them the odds and you do the exact opposite when you are out of position". That way you increase the amount of pots you are involved when you are in command. It can be a very efficient strategy, especially in live tours with less experienced players, given that you play a fairly tight-aggressive style. It is also quite often seen in online cash games, usually in lower stakes.
However, bear in mind, that as blinds get higher and higher in a tournament you cannot afford to keep doing that. For example, in a late stage when the average stack is close to 20-25 big blinds, if you open 4BBs from UTG, you are more or less committed in case another player shoves, and you keep bumping into tough spots.
Also, you need to take into account how your opponents play. If they have a tendency to call very often, it makes sense to open big with your good hands, even from late position. If on the other side, they are very aggressive, re-raising a lot, it makes sense to open small.
As the game develops, you need to experiment on different styles, sometimes even mix-up your game, in order to confuse your opponents.