"It was actually a cute gesture when he had it done," said Clay Russell, a former Schwarzenegger aide.
But the marriage disintegrated soon after Schwarzenegger left the governor's office in January 2011, prompting a modification in the portrait -- Shriver's face was erased.
When the painting was unveiled in the Capitol earlier this week, a blemish was visible where the pin used to be.
"It's too bad they couldn't remove it without creating a smudge that got a lot of attention," Russell said.
The removal of Shriver's image from the portrait was first reported by the New York Post. A spokesman for Schwarzenegger did not return a phone call requesting comment.
Schwarzenegger and Shriver had been married for 25 years when she learned he had secretly fathered a son with a longtime member of their household staff.