Materazzi had already been substituted when he was shown the red card on the bench for dissent during the final minutes of the 1-0 defeat.
"I don't think I said anything in particular to the referee, but these are the rules," shrugged Matrix.
"I believe in that moment of the derby that all the Nerazzurri fans - and I am one of them - would've asked the referee when he was going to blow the whistle.
"At the end of the day we cleared the air and that's where the matter ended."
Materazzi was defended by Inter coach Jose Mourinho in the wake of that derby defeat, in particular with regards to the provocation he receives on a weekly basis by fans in every stadium in Italy.
Specifically Materazzi - whose mother died when he was a teenager - is subjected to extremely cruel and vicious chants.
"This is an issue that has been going on for some time. The chants belong in a third world country, but in all these years this is the first time someone has so fully taken my side.
"This is why I thanked him in private and I also thank him in public. I just hope someone in Italy remembers that, two years ago, perhaps I did some good for Italian football "