Bizzarly this happened to me recently when I bough a mk 5 gti. The cover was wobbly. When I prised it off one of the mountings was missing from the engine bay. I still can't understand why that would be the case. The VW garage says that previously some garage would have pilaged it to use on another car and so on, and never bothered their back side to replace.
The new bracket was about a tenner so all is well now