Sorry mate, not meaning to be a smartarse, it just appeared in my head
I think you need to get it back to the dealer as the other's have suggested if it's under warranty.
If it's not, then check the sunroof drain tubes which usually exit under the front and rear wheel arches. That is almost certainly where the problem lies, (unless the seal itself is knackered), but I would still bet on the drain tubes.
I had a problem once with a leaking roof and it was just down to the bottom of the tubes getting crudded up, a quick blast from an airline fixed it, however you need to be real careful as you can easily blow the rubber tube right off the sunroof drain - hence take it to the dealer if you don't know what you are doing, cos it is a right twat to put the tubes back on - you need to drop all the headlining out.
To check if the drains are working or find out where they exit, open the sunroof and carefully pour some water into the rain channel, the drains will be in the corners of the aperture, they will run down the A and C pillars normally.
Look underneath the car to see where it drains. If the water doesn't go down, or goes down very slowly - then that is the problem.
Hope that is a slightly more helpful answer than my previous one :wink: