"The mayor pays his bills. He's paid his bill. Any minor discrepancy is accounted for," mayoral spokesman Mark McDonald said.
But critics say the slipup looks bad for a mayor who has vowed to come down on tax delinquents.
"If you're going to demand that other people pay their taxes and bills on time, you have to make sure you have your own paid," City Controller Alan Butkovitz said. "He has to lead by example."
Zack Stalberg, president of good-government group Committee of Seventy, lauded PGW for holding Nutter to task, but he said the issue "sounds sloppy on the mayor's part."
"It sends a bad message," Stalberg said. "There's a big issue in the city when it comes to money owed. People want to know that the mayor, the leader himself, is current and not delinquent."
One PGW employee, who asked to remain anonymous, said yesterday that at an internal meeting at the utility last week, workers were warned not to speak about the matter - it violates PGW's confidentiality policy - or risk losing their jobs.
"These bills are private matters," McDonald said. "What you have is someone disclosing a trivial matter."
The billing issue occurred at the same time that Nutter has been aggressively exploring a sale of the city-owned gas utility. PGW's union isn't happy about it.
"Everyone inside the union is outraged by the mayor's arrogance, but no one's willing to publicly talk about it for fear of losing their job," said a source with Utility Workers Union of America Local 686, who spoke on the condition of anonymity. "We only hope that Nutter's latest abuse of power ends any talk about selling the utility."
It's unclear just how long Nutter's gas bill had been outstanding. In general, if a customer is at least $300 in arrears for at least 90 days, PGW will send up to three letters of notification that a lien could be placed on the property, said Barry O'Sullivan, PGW's director of communications. If the bill is not paid for an additional 60 days, a lien is placed on the property.
A three-day shutoff notice such as the one Nutter received generally follows a 10-day shutoff notice.
O'Sullivan said there are a number of variances depending on a customer's payment history and circumstances. He added that public officials do not receive favorable treatment during the collections process and noted that PGW has an automated system.
On Twitter: @Jan_Ransom