Cayman rear shock gone soft.

[gadgit]

Had the Cayman for a year now, but over the last few months have noticed that there has been quite a bit of clonking going on at the right rear?
So, took the wheel off and all seemed fine. No broken anything, and all clean and tidy.
After attending Kimbolton car show I noticed the rear right bouncing quite a bit over the sleeping police on the floor....
When I got home I attempted the bounce the left rear and it was nice and firm.
The right rear will bounce up and down and therefore it is shot.
In the dealer for warrenty repair....

Car has only done 18,500 or so so I would not have expected this so early.
Just wondered, has anyone else had one go at the rear at this milage,
Cheers,

Gadgit