In Punjab, Hindus are 39%.

Not one CM of Punjab till date is Hindu. All CMs hail from one particular religious community & one particular caste within that community.

Yet, Hindus are not officially considered as "minority". Majority community enjoys minority reservations.Why?

The Modern Punjab state with its modern boundaries did not exist before 1966. Before 1966, it was called "East Punjab". It included Haryana region & parts of Himachal. It was Hindu Majority . The modern states of Punjab & Haryana were born after Punjab Reorganisation Act in 1966

For better understanding, here is a temporal illustration about the formation of modern states of Punjab, Haryana and Himachal