I have noticed that the rear number plate on my 3 month old Octavia Hatchback seems to be coming loose. When I close the boot lid, sometimes I hear a rattle sound and I know that I have to press one side or the other of the plate back back onto the body work to re-fix it. The material that the plate is made of seems to be too springy for the adhesive that holds it to the curve of the body work. There are no screw fixings, just what I guess is double sided foam tape. Has anyone else noticed this? Is it a problem, I mean if the ends of the plate are loose and rattle, will the plate come off altogether or will the fixings in the centre hold the plate firmly? I have thought about taking it back to the garage where I bought the car but it seems that the plate is fixed in the correct and normal way.

Get a drill out and fasten it properly yourself. 

I bet that it's on the left side of the registration plate. I've noticed the same thing on my Octavia, I'll just get some double sided tape/pad and re-enforce it.