Is it normal for a daughter and her dad to grow apart as she grows up?

My dad and I were always so close when I was little, but starting my freshman year (I'm a junior now), we just have not been getting along as well as we did. We still do stuff together sometimes, but on the whole we do better if we just avoid each other. So I'm just wondering if this is normal and if it isn't, then what can I do to help it?