It seems that there have been a few small changes in the suspension set up in recent years and I have heard that they have also had several changes of spring suppliers.
There were a series of post about spring problems from new owners in Australia but this was generally thought to be due to the car being badly tied down in shipping.
Our car seems to have been lower than it should have been even when it left the factory and it has never been tied down. As far as I can understand it seems to be getting lower all the time.
I agree that a series of bumps could cause it to jack down if the damper setting is too hard it should recover unless the damper setting is impossibly hard and I don't believe that is the case or ride would be completely rigid.