First words?

Belle loves our building doormen.  They know her by name and she greets them with huge smiles.  Yesterday afternoon, after an exhausting visit to Riverside Park's River Run Playground, Belle enjoyed her usual friendly exchange with the afternoon doorman.  When the elevator arrived and it was time for us to go upstairs and get ready for bed, I said to Belle, "Wave 'bye bye,' Belle."  And Belle waved, and said something that sounded an awful lot like "bye bye."  Just before we got in the elevator, and to see if the words were for real, I prompted Belle again: "Say 'bye bye,' Belle."  She, again, responded with two syllables that sounded like "bye bye."  Craig and I were elated.  We'll see if she can repeat this.  We may have a talker on our hands!