Drivers Door Rattle

[matt@ocd]

Recently picked up an 05 Caddy and just started to use it as a daily.
Got an odd fault that I've not seen in other cars before.
When closing the drivers Door, as the lock latches over it rattles. Almost like the door isnt catching or sealing soundly.
Neither the lock or striker latch are loose.
It's almost like it's the hinge in the lock that's loose.

Anyone heard of this before?
Don't want to just try a new lock if something else could be causing the fault too.

Thanks