At least that's what I'm getting from this article at the Boston Globe:
Kerry didn’t reveal his change of position during a news conference, like he called last week in Boston to air his views about the federal debt negotiations.
He didn’t do so in a speech on the floor of the US Senate, like he delivered with evident pride last month after Boston Bruins won the Stanley Cup.
He came out, if you will, in a more inert fashion last March, when his staff answered a survey from a Globe reporter inquiring about whether members of the state’s congressional delegation favored gay marriage and the repeal of the federal Defense of Marriage Act.
An aide, relaying answers Kerry gave during a brief phone call from an international trip, said yes to both survey questions.
When a story – about how gay marriage was no longer a political wedge issue – appeared in the newspaper a week later, a condensation mistake resulted in the senator’s job title and first name being left off a sentence reading, “A Globe survey of the Massachusetts congressional delegation shows support for gay marriage and for repealing the Defense of Marriage Act by Kerry and each of the Bay State’s House members, all Democrats.”
Good for him. About time. Though it seems as though Kerry's policy positions must always be fraught with confusion.