And the Reds midfielder celebrated by moving with the aid of an invisible walking stick.
The bizarre scenes saw his team-mates laughing as Liverpool picked up a vital three points in a close title race with Manchester City.
Georginio Wijnaldum had put Liverpool ahead before the spot kick with a low drive.
After the match Milner said: “Everyone keeps giving me stick about being old!
“We just need to concentrate on our side, all we can do is keep the pressure on by winning games.
“They (Man City) know they have to be perfect as well.
“All we can do is win the rest of our games, hopefully it’s good enough.
“Both teams have been pretty ruthless and clinical. It’s not easy week on week, we’ve lost one game and are second.”
Milner started on the bench and admitted it was difficult to watch his Liverpool team-mates try and overcome a resolute Cardiff side.
He explained: “Obviously I’ve got confidence in the boys and want them to do well, but it is a bit worse when you’re watching from the side.
“I thought we were in control for the majority of the game, you have to stay patient.
“It’s easy to be impatient and start playing the wrong way.”
Wijnaldum admitted it was very tough to overcome Cardiff on a dry pitch.
He said: “It was tense the whole game, it was really tough.
“We knew that, the situation that both teams are in, we knew they would do everything to make it difficult for us.
“The pitch was dry, there were no ball boys anywhere but we knew that.
“Of course there was relief when I scored, we are in a tough situation as we knew we had to win to compete with Manchester City.
“In other leagues we might win this sort of game four or five nil but not in the Premier League.”
Liverpool are now two points clear of Manchester City at the top of the table although Pep Guardiola’s side have a game in hand.