Former President George H.W. Bush served as a witness in a gay wedding ceremony for longtime friends in Maine last weekend, USA TODAY reported.

Bush, 89, and the former first lady, Barbara, attended the wedding of Bonnie Clement and Helen Thorgalsen, owners of a Kennebunkport store and friends of the Bush family.

A picture of the former president signing the marriage license was uploaded to Thorgalsen's Facebook page.

Gay marriage was legalized in Maine last December, becoming one of the first states to decide on the issue by popular vote.

"He signed the marriage license after an impromptu request from the couple," said Bush spokesman McGrath said.

Although gay marriage was not a hot topic during H.W. Bush's presidential term, his son, former President George W. Bush, openly opposed same-sex marriage and supported a constitutional amendment to outlaw it. However, his wife Laura and daughter Barbara have expressed their support for gay marriage in addition to his former Vice President Dick Cheney, whose daughter Mary is gay, and former Secretary of State Colin Powell.

When asked to comment on the issue in July, George W. Bush declined to comment, saying he "shouldn't be taking a speck out of someone else's eye when I have a log in my own."

Although he has largely stayed out of the gay marriage debate ever since his presidency, brother Jeb Bush, former Governor of Florida and potential presidential candidate, has said he believes it should be up to the states to decide.

Currently, 13 U.S. states and the District of Columbia have legaized gay marriage.