Mourinho was seen speaking with Huijsen after celebrating Benfica's 4-2 triumph.
He later explained, "Dean was my player in Rome. He's a friend of my sons. Our families know each other well, and I have a very good relationship with him. We talked about the game.
"The boy was disappointed, but I was telling him they were lucky to have lost by only two. It could have been more."
Benfica goalkeeper Antoliy Trubin was the hero, as his goal to make it 4-2 guaranteed a place in the round of 16 play-offs.
Mourinho also said: "In football, everything is usually déjà vu for me, but this is the first time it's happened to me.
"We knew Trubin could do this. We were losing in Porto a couple of weeks ago, and in the last minute he went up and scored. We know the big guy is capable of this. The most important thing is that the cross is high quality. You have to put the ball there. But it's an incredible goal.”
The Special One added, "When I made the final substitutions, Ivanovic and Antonio Silva, I told them it was enough to qualify. That they should close out the game.
"A few seconds after making the changes, they told me we needed one more goal, but I couldn't make any more substitutions. We were lucky to get a free kick and for the big guy to be able to get forward.”