Probably the clutches slipping, but it really depends on your dealer if it's going to get fixed. I suggest you take it in before the 3 year/36k mile mark.
Some people complain of shuddering and get an entire transmission and clutch swapped. Others have weird noises and jerkiness and the dealers brush it off as a characteristic of the car. All I can really say is take it in and I wish you the best of luck.
2012 FF Ti HB Kona Blue, DCT, Built 5/24/2011, 401A + Ti Handling Package, Parking Technology Package, Winter Package, Moonroof, and MFT w/NAV at v3.6 125k miles and counting...