Olivier Ntcham scored the game's only goal which brought Gerrard his first defeat as a manager, though the Rangers' boss claims that fourth official John Beaton told referee Collum that 'Gers' midfielder Ryan Jack was fouled by Celtic's Tom Rogic in the build-up to the goal.
Speaking to 'Rangers TV', Gerrard said: "He's shouting 'foul, foul, foul' down the mic.
"I just assumed it would be given. For me it was a blatant foul and if we get that we maybe come away with a point."
It is understood that Gerrard spoke to Collum after the game, and thinks he will "change his mind" once he reviews the incident.