What developmental milestone is this?

The other evening, I was getting ready to make dinner (waiting for Tim to come home to help watch Maya before I started the ACTUAL cooking). Maya was playing nearby in the kitchen, standing and oogling at "the baby in the oven." (This is how we refer to reflections... "the baby in the window," "the baby in the oven"...) She was happily giggling at her reflection when Tim came home. He walked in from behind her and said "Hello." She saw his reflection and got giddy. "Daddy! How'd you get in there?" After a few moments of elation, she determined to crawl to that daddy guy and get picked up. So she lowered herself to her hands and knees... and... crawled around the corner into the dining room (to the other side of the wall that the oven is on). After we got over how funny it was, Tim came from behind her to pick her up. She looked at him as if to say: "Wow! How'd you get back here so fast?!?!"