Mommy/Daddy to Mama/Dad now Mom and Dad

I was just remarking to John several days ago how I had noticed that in the last few days he'd taken to calling me "mama" in a soft, sweet little voice. It was very endearing, and melted my heart. At the same time, he had taken to calling John "dad" in conversation, both very emphatically when he wanted attention and very softly when he needed some lovin'. Now, today, I've heard it shortened even further to just "mom", although this morning when he was cuddling it was still "mama" and when he was crying for something it was still "mama". Tonight, from his room, I could hear, "Dad, come and play garbage trucks with me!" and "Dad, I want you!" And then, "Mom, I need you help me!" when he wanted me to clean up his mess instead of picking it up on his own. I can't believe the time has come when I'm no longer "Mommy" to him. It has not been that long that he's been talking, and now that endearment is almost gone. I know that I could not hold onto that forever, nor would I want to, but I guess I wasn't prepared for it to change so quickly, almost over night.