A former receptionist for Andy Warhol says she is auctioning off a 1965 self-portrait the late U.S. pop artist once gave her as a gift.

Cathy Naso, who earned the gift through her hard work at Warhol's New York studio, said she decided it's time to part with the valuable piece of art work, The New York Times reported Friday.

"I'm older now and I'm not looking at it," Naso said. "I began getting nervous that something might happen to it."

Experts estimate the painting could fetch up to $1.5 million at Nov. 11 Sotheby's auction.

Naso said even when she was not being paid to work at The Factory where Warhol created his works, she would volunteer her time to be around him.

"I just wanted to be there," she told the Times about the cult following Warhol drew to the studio. "Andy ate yogurt, so we ate yogurt. We idolized Andy."

Warhol died of heart failure in 1987 at age 58, not long after gallbladder surgery.