My first tooth

The past month and a half or so we have had a little drooling machine on our hands. Lily has also been putting anything she can think of in her mouth to chomp down on, our hands seem to be her favorite, although her hands are a close runner up as you can tell. Today when Lily decided that Corey's hand would be a good gumming tool, he felt a hard lump on her lower gums. Her first tooth has popped through. We are excited about this next step for Lily, but saddened at the same time. How is she growing up so fast?