There have been several smaller leaks since that massive blowout, including two this month.
On Monday, elevated methane levels showed up again on an independent monitor, lasting 24 hours.
Southern California Gas told Eyewitness News there was no release of gas over the holidays, but they only investigate levels over 7 parts per million. Monday's peaked at half that.
The company says gas readings at lower levels can be caused by things like idling vehicles, barbecue grills and space heaters.
Residents were not convinced by that explanation. They registered health symptoms on a local tracking app while others took to Twitter to vent their frustration.
Porter Ranch residents claim new leak near SoCal Gas facility
Local resident Patty Glueck wrote: "Thanks @socalgas for the gift of methane, mercaptans and other toxic chemicals (which you refuse to name), nosebleeds, asthmatic attacks, bronchial coughs, migraines that you've given those near #AlisoCanyon for a Christmas present. Let's hope this unsafe site is closed in 2018!
Andrew Krowne, owner and creator of the Environmental Health Tracker app that helps residents report symptoms, said on Christmas Day there were about 400 symptoms reported by more than 120 people, with levels reading at 3 ppm for the day.
He doesn't believe the gas company's claims that residents are not at risk and notes there was a leak observed earlier in the month as well.
"It's BS," Krowne said. "The leak we had on Dec. 18 was met with 34 people reporting about a hundred different symptoms. That is scientific proof that their releases cause illness in this community."