I would lean towards no. I'm me. I don't consider the things that people seem to associate with their "inner child" to be exclusive to children, so I don't feel a tension between my desire to act responsibly and my sense of wonder, joy, and playfulness.

Age isn't a mask hiding the inner child, it's a toolkit that helps them appreciate and engage with those things. My childish delight at birds flitting about the bird feeder is only enhanced by being able to buy my own, keep them filled, and the ability to understand more about everything that goes on with them. I have the experience and faculties to answer questions I have, which only deepens my appreciation for the "common" wonders we see everywhere. Experiencing more of life and it's lows only makes the highs sweeter.

A child plus age and experience is an adult. You don't need to lose the happiness to get there.