Mama, for real or babble?

So yesterday Garrett said "mama". Now he has been saying "nanana" for a couple months now and babbles non stop. But yesterday he was saying "nanana" and I said, "mama." Then he said "mama" right after. Later that day he said it a few more times. Then today he said "mama" again 3 times. So, is it the real thing, his "official" first word, or is this just babble?
*Let's take a poll: Let me know what you think. Can I count this as his first word and right it in the baby book???