Brake pedal pulsating

Hello, sounds like a probable brake rotor concern. The brake rotors may have become out of round, causing pulsation during braking. A repair shop should measure the brake rotors, check the brake pads, and check for brake rotor runout - the amount that the surface varies in thickness or warp when checking all the way around. I'd actually suggest seeing your local BMW dealership to have this assessed underneath the terms of vehicle warranty.