Around 10 minutes into the second period, the Blues duo exchanged angry words on the field. Matusiwa was still having to be calmed down by his boss and team-mates after the final whistle.
“I don’t know the details of it,” said McKenna, when asked about the incident. “Both were emotional in the game, both trying to win the game.
More:McKenna’s verdict on ‘frustrating’ home draw with Watford
“They know that it shouldn’t happen on the pitch. These things happen all the time at training ground and behind closed doors, but you don’t want it to happen on the pitch. You don’t want to give off the wrong impression that the boys aren’t united because those two are.
“It’s just a bit of passion that’s split over but they both know that it needs to stay in-house and that these things have to be discussed in the dressing room. The players discussed that downstairs themselves and they know that.
“Those two boys will learn from this. They’ll both be ready to help us get the result on Saturday (at Swansea).”
More:Sindre takes another step forward for Town – AJ’s player ratings from Watford draw
More:Leif Davis injury update following his absence from Watford draw