My parents do this to me, and while I don't want to go so far as to say that I'm "annoyed," I do find it irksome. But my younger sister was killed in a car accident a few years back, so I just have to think that it makes them feel better. They obviously don't think that I'm, like, driving around with my eyes closed, but what if something happened? Would they blame themselves that, "Oh my God, we didn't ask her to drive safely!"?

Just smile, say "okay," and give them a kiss/hug goodbye. It's not hurting anything, and it gives them peace of mind. They just love you! :) (And I've picked up the same habit and do this to all my loved ones. Dorky, but it's one say I say "I love you")