2002 BMW 530 Transmission Problem

Hi,
I just bought a 2002 BMW 530i. I have a problem coming from transmission. Acceleration is fine but when I come to stop and the speed approaching 10 mph, I can feel a little jerk in gear changing. It feels like gear changes from 3rd to 2nd and the transmission jerk a little bit. What could be the problem. I want to fix this before warranty expires. Thank you