Mat,
This story was originally titled, "Tagging the City." It was changed to something that I felt better fit the double meaning of the father's mindset and how the son was trying to change it, as well as the obvious perspective as seen in the son's final art piece. But, as you mention, the underlying motivation and pscyhology of "tagging"--although not really explored in the story--was certainly in my mind as I wrote it.
Jake