Uruguay international Suarez scored in the seventh minute of added time - his 30th goal of the season - to snatch a point for the Reds, but his scoring exploits were overshadowed by what went before.
In clashing with Ivanovic in the penalty area the striker appeared to bite the defender's arm, but referee Kevin Friend did not see the incident and despite the Chelsea player's protestations took no action.
Suarez rubbed salt into the wound by heading home Daniel Sturridge's cross with virtually the last touch of the match with the clock showing more than the six added minutes.
Liverpool striker Sturridge cancelled out Oscar's 26th-minute opener with an equaliser seven minutes after the break before Eden Hazard's penalty - after Suarez had handled - regained the lead for Chelsea.
"I thought it was an emotional return," said Benitez, whose name was frequently chanted by fans who remember him fondly for the 2005 Champions League triumph.
"I was pleased with the reception of the fans and disappointed with the late goal conceded - especially as I couldn't understand why there were six minutes and 45 seconds (added on).
"It is a strange decision. Some games you have six substitutions and they say three or four minutes but six minutes (had expired) and with a throw-in for us the game was over.
"But six minutes and 45 seconds is difficult to explain. We need to analyse why we didn't stop the cross and they scored but in the normal circumstances we would have finished the game.
"I didn't see the incident that people are asking me about. I have not spoken to the players (about Suarez). We were talking about the late goal - it is very frustrating. We have plenty of time in the week to speak about it."