It's either there with the big continuity clasm that has Luke asking Leia what she remembers of mother: "She seemed sad a lot" (well she did for the minute she lived after they were born), or it's like the good folk above suggest.
He had to show at the end of Return of the Jedi that Anakin was finally redeemed and so had him appear ghostly with Obi-wan and Yoda. Then he noticed that when Jedi die in TPM and AotC nobody disappeared. Ouch. So he set up that idea that it's a new thing learnt by Qui-gon.
no subject
I'm not mega bothered. He (Lucas) clearly needed to make some plot device whereby Luke and Leia were divided, and the only way was to kill off Padmé.
He had to show at the end of Return of the Jedi that Anakin was finally redeemed and so had him appear ghostly with Obi-wan and Yoda. Then he noticed that when Jedi die in TPM and AotC nobody disappeared. Ouch. So he set up that idea that it's a new thing learnt by Qui-gon.