Sudden sleep changes at night

For the past week, it has been a bit more difficult to get Tristan to sleep at night. He still sleeps around 9PM every night and sleeps through the night. The problem is that he relies on us more in putting him to sleep now. In the past, Jean-Louis would take him upstairs and put him down and leave right away. Tristan doesn't fuss at all and if he doesn't sleep right away, he will minutes after. It really has been more or less that easy for us since he was sleep trained at 6 months old. Lately, when Jean-Louis steps away to leave, he freaks out. Jean-Louis has to come back and stay for him to calm down and lie back down. He doesn't pick Tristan up, he just stands at the end of the crib. That is enough to make Tristan happy.

Tonight, it was my turn to put Tristan down and watch him sleep. Yeah, we take turns now too. We want Tristan to get used to us both putting him down at night. We have both learned quickly in the past week that Tristan will not cry at all if we just put him down and stand nearby for a few minutes until he is super sleepy or asleep. It's a bit of a dependency but it's not too demanding on us and it sure beats him crying hysterically. I have forgotten how much his crying bothered me :(

When I put him down earlier tonight, I slowly walked away just to see what would happen. He sat up and started to protest so I stopped and turned back. He then laid back down and tried to sleep. After a few minutes, I tried again and got to the door and out of view. There was no response for a few minutes but when I was about to leave, he whined a bit so I walked a bit closer. He then tried to sleep again. I made another attempt to leave and he actually stood up and tried to peak around the corner to find me so I made myself visible. He didn't fuss at all. He just wanted to know that I was still there. He laid himself back down right away and tried to sleep. Then I started to hear him breathe. There was actually the sound of him breathing and I took that as a sign that he was finally asleep. I was right :)

I was in the room with him for 7-8 minutes. He didn't cry at all but I had to be there. He's obviously scared if I'm not. One night, Jean-Louis stood in the room for around 15 minutes. Another night, it was just 1-2 minutes for me. It all depends on how tired he is too.