Moms boyfriend looks in my room??

I recently moved back into the spare bedroom at my moms house (which technically her boyfriend owns) and they said they didn’t mind at all. I was in an abusive relationship for 5 years and finally got out and they would tell me every time I came over that the room is available if I need it. Anyways, I don’t pay rent and they made it clear that they don’t want me paying rent because they can afford it and I’m barely home. I always clean up my mess and leave my room spotless when I leave.. but the other night he mentioned that he opened up my door and was pleasantly surprised that it was clean.. which he didn’t say rudely or anything. I just found it kinda odd that he would even open my door and check what it looked like since I always keep my door shut and that my personal belonging are in there. He’s even made comments of somebody who rented a room from him back then.. he would look in there when they left and it was a pig sty which I think is wrong to do. Do you find it weird that he would do this? Or do you think it’s normal since he owns the home? Maybe I’m just not use to somebody looking through my room.. because my parents never did that growing up. They kind of let me have my own space as long as I didn’t make a mess in the rest of the house. Btw I’m 21 years old so it’s not like I’m a minor and need my room to be checked up on. Maybe I’m over thinking it.