“Do you think this is a step in evolution happening before our very eyes?”
No. It’s a learned behavior, as the article makes fairly clear (it really doesn’t matter that the others haven’t done it.) Something similar has been seen in wild chimpanzees, who learned to make loud dominance displays with metal cans, which thereby increased their social status.
In addition, evolution occurs only in populations, not individuals. It can be considered a “step” if it increases his mating opportunities, and he passes on genes to his offspring that perhaps influence learning, and those genes spread. But that’s very unlikely in a zoo situation.