Animisa Locana Pooja. Is it really what it is?
"Animisa Locana Pooja" was indeed an act of gratitude to set an example to the world. It was also done to sanctify the tree as it would become the symbol of the Buddhahood. 

The story your friend has told seems to be his own imagination. King Suddhodana was doing all he could to keep prince Siddhartha in lay life. So showing gratitude to him for aiding in the quest of attaining Buddhahood is out of the question. In any case, the Buddha later visited his father and saved him as well.


  But there was still doubt within himself as to whether he was actually
  a Buddha
  Blockquote


The Buddha is omniscient. He has no doubts and needs no 1 week long mental conversation with a tree to know something :)