So once we were all on the elevator (including the aforementioned gentleman), I gently, calmly (and quite quietly) asked Gerry to turn it down again. He said no. So I gently touched his head and leaned down close and told him it was too loud for when we were on the metro so we needed to turn it down or we couldn't have the iPhone out. He then turned it down and I said Thank you.
The gentleman then said to me, "Don't expect that kind of cooperation for the next 10-12 years!"
I smiled. Then I noted that "He does pretty good, doesn't he?" in reference to Gerry. As we got off the elevator I joked that he should give me his number so I could call him in 10 years.
Will cooperation always be that easy? Well, I don't know. If the gentleman knew all of those things, would he still have thought it was "easy?" I do know that I do not expect blind obedience from my children. I try to treat them respectfully and to guide them as they learn to offer the same to others. Is it always easy? I guess not. But no one ever told me parenting would be.