LotR -- Book 6 - Chapter 4 - The Field of Cormallen

[Hilde Bracegirdle]

The real question is how is it the eagles kept Frodo and Sam from falling off? I suppose they were exceptionally skilled, from all the practice!

But this following quote I found very curious.

'Twice you have borne me, Gwaihir my friend,' said Gandalf. 'Thrice shall pay for all, if you are willing.'

Is this simply a strange turn of phrase or is Gwaihir paying Gandalf back for a favor we are unaware of?