What to do when your 17 year old stepdaughter says that parents should not know their kids?

My stepdaughter got into an argument with her father last night and told him that parents should not know their kids and kids don't need to know their parents. After telling him this, she asked her father for a pre-birthday present because she needed a GPS. Her birthday is not until July and then announced to her father that she would not be coming to FL for the summer.