"Mom"

As I was standing at the island in my kitchen this morning, making school lunches, I heard in the sweetest little voice "Mom." Almost in the form of a question, as if she was about to ask me for something. After almost passing out, I quickly looked around to see if it could have been Ryleigh or Liam talking to me. When I realized they were no where to be found I looked down to see this little girl, looking up at me with a little smirk on her face. I screamed with excitement, which brought the other 2 running in to see what was going on. When I told them, they acted like that was no big deal they had been calling me mom for years. I quickly told them "you don't understand this is the first time she has said it on purpose and without yelling it at me!" They still didn't care too much and continued on with what they needed to do to be ready for school on time! Still amazed, I called Dev and told him the exciting news.
All I got out of him was "Really?"

Why is it that no one is as excited as me about this?I'm sure it won't be too long before I will wish she would stop saying it!