19 years old, concerned about receding hairline (pictures included)

[Lawrence1]

Hi guys. I'm 19 years old and I've just started noticing my hairline moving back farther than it used to be. I have pretty long hair, so sometimes it's hard to tell, but when I move back all the hair, the temples look like they're starting to go back pretty deeply, especially on the right side. The hair around my hairline also looks thin.

I'm not sure if this is just a maturing hairline or if I should be concerned about balding, it definitely runs in my family, and if I should get on propecia or something. Thanks!