i agree with this. it makes more sense. Dumbledore would have know that he can't leave the sword to Hp. Mor importantly, I do think that Neville got the sword not to prove that he is a true Gryffindor, but to defend the house. The sorting hat has in the past givin Harry the sword for hte same reason.
It would seem that the sword is not subject to the normal rules of possession and maybe Griphook should have thought about that before claiming the sword in payment. HP had no right to give the sword away and if Griphook was not so proud and arrogant he would have thought about it. It's not like the sword was lost from sight. Everyone knows it's been hanging in the headmasters office at Hogwarts and if it was possible for someone to lay claim to it, it would have been done already by some other Goblin! The sword may have travelled a bit but never became anyone's property and when needed it returned to it's rightful place.

But this is all speculation and it would have been great if this was alll in thte book. I's nice that JK cleared some things up in her interviews, but i for one, wanted to read it in the book.