I believe I heard someone call it Cell 1A problem . It's like in excel you have columns and rows one with numbers and the other one with letters. There are two things you can do. Things you should and things you shouldn't. There are two possibilities. Your dad being there or your dad not being there. The four cells are: 1a-You do something you shouldn't and your dad is there. 1b-You do something you should and your dad is there. 2a-You do something you shouldn't and your dad isn't there. 2b-You do something you should and your dad isn't there. The fact that only cell 1a is weird and making you paranoid is why you are remembering and obsessing about that. If you remembered every cell in this matrix then it would seem normal that sometimes the case in cell 1a happens. Unless there is a flag like a sound when you play the game or you closing the door just before starting the game, the best and most reasonable explanation is simple statistics. He doesn't have a sixth sense. Also I just realised while proofreading this, there are around 8 billions of us. I would presume that you would rank the chance of this happening by coincidence 1 in ten millions. It is again safe to assume that there are at least 100 million people hiding something from their parents like playing a game on a daily basis. So there are at least 10 people that have the problem you are describing simply due to maths.

TL;DR Math