Son And Daughter

My three kids came home from college for the holidays. Almost immediately, I was inspired and elated about how my 20 and 22 year old son and daughter were getting along. Even my wife was blindsided by how well they were getting along. They spent time with each other at home, running errands and basically did everything together.

A few nights into the holiday break, they were in the basement playing Fortnite. I could not care about the game and it was time for me to sleep anyways. Two hours later, my wife says what is that noise? Sounds like outside but I slowly walk into the living room and I hear my daughter in what sounds like sexual distress. It is muffled and low, but she is moaning. We choose to not want to know anymore, head back to our room and turn on the fan on the headboard. 15 minutes later my son and my daughter come up from the basement. My wife says wtf?

The next night, same thing. This went on almost every night and is still going on now.

They go back to school in about a week or so, so it will stop. Should we mention anything to them?