Museum marketing manager Kate Oktay said the past few events were targeted by online scammers operating from overseas and there was a chance it could happen again.
Scammers had been creating fake profiles on social media sites, often Facebook, and saying they had extra or unwanted After Dark party tickets to sell.
Victims would then pay money into bank accounts, but never receive a ticket.
"We ... hope that no-one falls prey to it this time," Ms Oktay said.
People should only purchase tickets from the museum website and avoid unknown sellers online.
Unvalentines, on February 12, will have a tattooist working on the night providing $50 tattoos, a fortune teller, DJ set by Radio One DJ Jamie Green, a cash bar, Planetarium karaoke; and many live interactions throughout the museum.
