Although it'd be unusual, it's possible that the door stop bolts weren't tight enough and that it's either moved or was previously misadjusted. That "ASSUMES" that your door latch assembly (in the door itself) isn't the cause of the problem. Try some WD-40 in the latch assembly too as that could help if it's a corrosion related problem.

The door stop, the part on the front "B" pillar is adjustable by loosening its two bolts but it can move alot if loosened too much so loosen it slowly and just enough to be able to barely budge it inwards. It can be adjusted up/down too and if off too much it won't align with the door latch at all when closed.

If the door latch assembly itself is the cause (and they've been known to have a few problems, mainly with door lock actuators), it'll need a replacement door latch assembly from your dealer as it's not serviceable short of lubing it with WD-40.