"Today’s his tenth birthday. He’s a very emotional young man. He likes to solve other people’s problems. One time... Posted by Humans of New York on Thursday, September 3, 2015

Brandon Stanton, the photographer known for his widely followed photo series Humans of New York, is currently traveling in Iran, where his portraits of everyday Iranians — each appended by a caption with heartfelt quotes from the subject — are doing important work in humanizing a people who are too often vilified in America and in Washington particularly.

Earlier today, he posted a photo from the northwestern Iranian town of Tabriz, showing a father with his 10-year-old son. The caption is a quote from the father, lovingly describing his son's "humanitarian" spirit. It's very sweet. Shortly after the photo went up on Facebook, it got a comment from a surprising source: President Obama, commenting via the official White House Facebook account.

Here is Obama's full comment:

This is not a meaningless moment. The official American posture toward Iran has for decades been one of overt hostility. The last aberration from that was almost 20 years ago, when the Clinton presidency briefly attempted a failed outreach to Iran. But otherwise American rhetoric has sent a consistent message of enmity.

Obama, it is easy to forget now, came into office pledging to reach out to Iran and particularly to the Iranian people. That was often controversial: His 2007 campaign promise to talk to Iran was widely mocked and derided. His annual video messages to the Iranian people, on an important holiday called Nowruz, have been derided as too soft, particularly after the 2009 "green movement" protests and crackdown. And the sense that Obama is insufficiently hostile toward Iran has dogged him throughout the nuclear negotiations.

All of that is to say that Obama's repeated gestures of comity and warmth toward the Iranian people are, truly, unusual. His expression of hope that he might one day meet this 10-year-old Iranian boy has subtext to it: That meeting, unless the boy immigrates to the US, would likely require a substantial change in the nature of US-Iran relations.

Obama has been careful not to couch the Iran nuclear deal in terms of a detente with Iran, and indeed the deal neither delivers nor relies on such an easing of hostilities. But there have been moments when the president has betrayed an ever-so-slight hope that tensions could ease. Maybe I'm reading too much into one Facebook comment on a heartwarming photo about fatherhood, but the fact that the president chose the unusual step of leaving this comment, and that he chose to leave it on a photo of a father and son in Iran of all places, seems meaningful.

Watch: What I learned by befriending Iranians on Facebook