It's normal, especially in dry air. Electric charge from your body builds up when you rub on carpet or your cloth seats much more in drier air. Once you touch metal, the "static" causes the shock. This is the reason why you're not supposed to go back into your car before you finish filling up your gas tank. Some people have died because they go out to fill up gas in cold weather, go back into the car and charge up more "static," get out again and touch the metal part of the gas hose before touching any other metal parts, and ignite static electricity with the gas fumes. So, it's normal, but be careful when refueling. I usually touch the door handle only because it's plastic. But when you're refueling, it's better to just get shocked before you refuel.