2003 Ford Falcon vibration

There's three common causes of this if it occurred immediately after the new rotors were installed. By far the most common cause is failure to use a click-type torque wrench on the lug nuts. Every manufacturer publishes the torque specs for their cars. That will prevent damaging the threads, breaking the studs, and warping the rotors from uneven clamping forces.

The next thing to suspect is rust or scale broke off and got stuck between the rotor and hub. You can identify that by raising the car off the ground and spinning the wheels while watching for "lateral runout", or sideways movement in the wheel.

A less-common cause is rough handling of the rotors when they're being shipped. Many mechanics measure the runout with a dial indicator to find that. Usually machining them will solve it.