Ayezee

Hello everyone. I am new to this forum and I am really hoping someone would be able to help me with my query. I have a 2007 GS430 with only 70k kms clocked. Recently I had got my brakes actuator replaced with a brand new one. Brakes work fine ever since with no warning signs anymore however there is this intermittent buzzing sound from somewhere around the actuator. Lasts for about 2-3 seconds everytime sometimes even right after I have switched off the engine. The sound is like a phone on vibration mode kept on a table. I have asked several people around who says it is normal however I didn't have this before and thus can't be 'normal'. Does anyone have any idea what it could be?