The Name is Mommy

Emmett has started calling me Mom.  Or, if he is feeling like it, Mama.  I have NEVER been Mom or Mama.  He says it with a straight face and ALL THE TIME.  I am not sure what he is testing out.  Limits?  My patience?  Whatever it is, it is weird and I don't like it. (insert foot stomp here)  I am really, really hoping it's just a phase.  I am not ready to be Mom yet cause....he's still a baby.  Right?