"C1201 trouble code is common on lexus when the brake pads wear out and the the caliper pistons extends to maximum. It will cause the brake fluid to drop and the brake fluid level sensor is activated. Once the bake fluid level sensor is activated for more then 4 seconds, It will set the code C1201 in the system. Check the brake fluid if it is at minimum. Even though the light may not be on but when you go up / down hill it will illuminate for more than 4 seconds and that is what trigger the trouble code. By adding a little fluid and resetting the code you can prove that this may or may not be the probem. However to fix the problem , check and replace the brake pads as neccessary. Only then top up the fluid level to the maximum level , reset the trouble code and that should get rid of the trouble code till next brake job."
The vibration you are feeling decelerating from 60mph is NOT normal. You either have bad pads, warped rotors, or both. I would take the car to a trusted independent mechanic and have the entire brake system looked over. Good luck!