Picked up my spangly new GTI only 2 weeks ago. Being a virgin VW owner i have to say i love it

Still running her in so not pushed it yet but i cannot wait when its time....
My only slight niggle with the car is an annoying rattle coming from the rear of the car. I have removed everything from the boot (even the floor lining!) and checked all the obvious areas. I think its either coming from the boot lid or even the light cluster.
When i shut the boot lid i hear a rattle then so i am assuming that this is the noise i hear when i drive over a bump.
Anyone experienced this or got any ideas before i give in and take it to my useless local dealer?