Pavement vibration won't do that unless you've got some very unique pavement or are running your tires so high in pressure that they may as well be solid steel.

If your fingers are going numb you probably need to hold the bars different, alter the angle of them or just not squeeze so hard. Your wrists should not be overly bent when holding the bars and the brake levers should be in line with your fingers when you're palms are on the bars and you hold your forearm, palms and fingers all in a very straight line from your normal riding position. That way you don't need to bend your wrist up or down to squeeze the lever.