Interesting...
To me the VE and the VF holds a lot of resemblance as far the body that I think there is some that you can check real quick and cost nothing.
On my VE/G8 the door striker rattles and makes noises like the one you described.
I used some electrical insulation tape.
Wrap a couple of loops around the B Pillar striker, just enough to make a snug fit when you close the door.
The door will feel a bit tight when closed.
Take it for a spin and see if you can hear the rattle.
If that is the case and happens more on the driver side is the Striker wears out pretty quick and the door lock has play on it.
With the car flex and the door just barely hanging hits the striker making a rattle sound.
On the Pontiac G8 the solution is to replace the striker but in my case, tape has been doing the trick just fine for the past 4 years and keep going.
The tape acts like a plastic bushing that keeps the lock snugged and soft enough to wear out without damaging nothing else.
Try that as a test and see what happens.
Also it could be as simple as some inside the pillar (tool or hardware) dropped during assembly and is making the sound.
