Car Warranty Coverage

Hi ....
I recently purchased a 2000 323i w/45K that was well maintained. I took it a mechanic to check out why the front end would shake when the brakes were applied, since new rotors & brake pads were installed at 35K. I was told that I needed new Ball Joints for both front wheels. I was wondering if anyone knew if the manufacturer (for BMW) would have a warranty on the ball joints? (since the car is still under the New Car warranty til 50K) Otherwise, BMW is probably going to hit me up with a large invoice. It just seems to be that the ball joints quit way before they should have.
Anyone else have this problem?

4 years 50 thousand miles from inservice date is all you get, unless you pay to have it extended.

yeah to extend for an extra 15k miles they hit me up with 2,200.00