Whistling?

Lexi has started doing something that I have NEVER heard a baby do before. She is actually whistling. She puckers her lips and blows a soft whistle. The first time I heard it, I thought it was a fluke, but she keeps doing it over and over again. I don't know where she got it. We aren't big whistlers and I can't see her teacher doing it, but you never know. Perhaps, she accidentally discovered it and likes the sound or our reaction.

By the way, her top left tooth finally cut through the day before yesterday. It looks like the other one isn't far behind.