Is It Normal To Have A Dip Or Ridge Along The Top Of The Skull Where Headphones Rest?

Hi, I have a kind of strip along the top of my head ranging from one ear to the other where your headphones sit and I m not sure if that s normal or if I should get it checked out. I ve tried looking at images of skulls and they all seem to look smooth but mine goes up and then at to top has a bit of a dip them goes back up again to them come back down to the spine. Is this normal?