Need another perspective

I and my S.O. have been together for almost 6 years. When we first met, I had already had a home purchased and he later decided to move in with me. We now have a 3-year-old and at the beginning of this year, we both decided to get an apartment together in the next city over to get away from the increasing crime and have our son in a better school system. We got the apartment in January.

I also started a new job then and I work overnight about 3-4x a week. On the nights that I work, he will go stay at the apartment by himself and leave our son with his mom overnight and his reasoning is because the apartment isn’t fully furnished yet. But we have a bed in our bedroom and a toddler bed in the spare room so far for starters. But If I am off work, he and our son will stay at our old home.

If I am away for work, he has never stayed overnight at the house by himself or with our son, In the past if I'm not there, he would stay over at his mom’s house. Is this weird?