After having my first child with Luke, I noticed that he would sometimes just stand in front of the star lamp in the baby's room.
I think it was the 9th of Fall, year 2 (The day my baby was born) that I first noticed this. I'm pretty sure it happened again on the 16th, both times after 18:00. I could be wrong about those dates, so once I get to Monday and Tuesday again I will let you know if it occurred then too!
The most recent time I noticed this occur was Sunday, Fall 21 year 2 at 19:00. Once Luke got back home from his parents', he immediately went upstairs and walked towards the star lamp in the corner, not leaving that spot even if I interact with him, and he never ended up leaving, even after 12am. I managed to get a video of him doing this.
Game Platform: Steam (PC) with Keyboard/mouse
Game Version: v1.1b-1237
In-Game Time/Date: 19:00, Sunday, Fall 21 year 2
Let me know if anything else is needed! I'll send my save file in a sec 

