Scirocco Central

hi all, I have a question and its been bothering me for a while but on my scirocco fuel cap should it stay locked because every time I lock the car and push the fuel cap after 5 minutes it opens and just clicks back it doesn't stay locked, all it is is a push in mechanism
Any help?
Thanks guys, Lawrence

It should lock when the car is locked. I've have had it stick shut when can be a pain which some GT85 sorts out but should not stay unlocked.