Repairing door frames...?

I recently moved into a new-build flat, all dry-lined plaster-board walls and architrave doorframes. during the usual diy inspection of the place, i noticed that some of the doorframes are cracked and away from the wall, from previous slamming of the doors i can only assume. does anyone know the best way to repair this, i am unsure whether i have to remove the door frame in order to repair it, or is there some kind of fixing i can insert, etc? all help and comments are appreciated.
Answer
Caulking is nice just remember to get water soluble and to use a wet rag tokeep your finger wet so it smooths down well and to wipe the excess on as you go as for the wood filler the best kind comes from minwax yellow container you dont need the two part though just dont put it on thick so it requres less sanding