In what ways could 'Good Boys Deserve Favors' be considered a coming of age story?

In 'Good Boys Deserve Favors' the narrator talks about how he picked the double bass because he thought the idea of a small boy playing a big instrument was funny. This is a childish and not very serious reason for picking an instrument. The boy shows his immaturity by not really caring about playing well and not bothering to practice. His interest in the instrument is in the instrument itself, rather than playing it. He cannot be bothered to learn bowing technique, but spends ages learning about the history of the double bass. When he is suddenly put in a potentially embarrassing situation, the instrument seems to pay him back for his interest and respect by playing beautifully. If the double bass represents his childhood, then this might be one last song celebrating his youth and innocence. After that day, he falls and breaks the instrument. He decides not to carry on with lessons, as he will be growing up and will have new concerns, including girls.