Children and grief

My daughter is an amazingly intuitive, sensitive, and expressive 3 yr old.  Over the past 11 months, I have been in awe of how she is processing her grief.  I have watched her go through the early stages where she repeated my account of his death. She spoke of wanting to die and go to heaven with Adam.  She asked questions about how and why. She took to gathering his belongings to bring her comfort. Things I would expect from an older child. Over the holidays she surprised me with her ability to express her feelings to me. While taking down the Christmas tree, she began to cry saying goodbye to the tree. Although I found it odd, I knew it was more than just a goodbye to the tree. I asked her what was wrong. Holding her, she said "I never got to say goodbye to my daddy". How at 3 yrs old is she able to vocalize her feelings better than some adults I know?