Mama's room

In our cozy little house we have three bedrooms- TeenIlla's room, Littlezilla's room, and Mama's room. Not Mom and Dad's room. Just Mama's room. Even though Dad sleeps there too when he's home (and hasn't been banished for snoring). And inside Mama's room is Mama's bathroom and Mama's bed. I'm not sure how this came about other than I usually refer to the room as "my" room and since the boys call me Mama it just evolved from there. And since A is not here all the time, the boys don't hear it referred to as anything else, like "our room". I even catch A referring to it as Mama's room on occasion. Poor A has no corresponding spot of his own, except perhaps for his closet. Wondering if this is a common occurrence or unique to our family.