I am starting to see this myself. I am very slow in the hills, I tend to grip the bars for the life of me in an apparent attempt to "help" my bike and am at least in the lowest gear in my middle chain if not my granny gear when the fast men and women zip past me... yet... the downhill side is quite fun

On my long ride last Saturday I had right at 45 miles of flat roads that followed 20 miles of hills and rolling - and that was just too much "flat" at the same time. Apparently hills are beginning to grow on me

Repeating the same hill sounds like a great way to practice!