The 911 domestic violence call that sent cops scrambling to Lane Garrison's apartment was triggered by a dispute between Lane and his Playboy Playmate girlfriend over who got invited to a funeral ... TMZ has learned.
As we first reported, Beverly Hills police went to Lane's house Monday night after someone in the apartment reported the incident. No one was arrested, but Lane was taken to the hosopital for an unrelated medical issue.
We've now learned ... Lane's girlfriend, Ashley Mattingly, was upset that Lane was invited to her ex-boyfriend's funeral earlier in the day but she was not. It is unclear why the family of Craig Rogers made Ashley persona non grata, but we're told it triggered a heated argument between Ashley and Lane.
Ashley -- who is up for Playmate of the Year -- felt Lane should not have gone to the funeral because it showed disrespect for her.
As for the hospital visit ... sources tell us when cops arrived, Lane had a panic attack, so he was taken to the emergency room and released shortly after.
As for why he had the panic attack, we're told Lane has been vigilant about keeping his nose clean after getting released from prison in a manslaughter case. He was driving under the influence when his car crashed and killed a 17-year-old high school student who was a passenger in the car.
We're told no one was injured during the argument. If cops would have seen any trace of injury, an arrest would have been made.