From Mama to Mommy

In the past week my wonderful first born, Brenna who is 2 1/2 began calling me "Mommy"! It is strange to hear after being called "mama" for the past 2.5 years. I feel like she is all grown up and I don't know what to do. It is so adorable listening to her because she says "mommy" with such enthusiasm and purpose. Brenna seems to end every sentence when she is talking to me with "mommy" for instance she will say "I love chocolate, Mommy" or "I am going to color, Mommy" it is so cute. When did your kids start calling you Mommy like a big kid???