It sounds like you are driving enough and for a long enough duration to keep the battery properly charged. You should not be having battery problems with a two year old car. You may have a problem with your charging system or something electrical is not properly shutting down when the car is turned off and it is draining the battery. The blue tooth module on older model X3s sometimes have this problem.
If you are under warranty, I would take it to the dealership to get it checked out.
2013 535i - ED, Oct 2012 | Cashmere Silver | Oyster/Black Nappa Anthracite | ZCW | Sirius | Air Blue 80
2008 X3 | Monaco | Sand/Black Light Poplar | ZAP | ZPP | ZCW | Xenon | Rear Fog
1988 Grand Wagoneer | Burgundy | Ghost Flames | 360 ci | Holley carb
BMW CCA #422951