"Did I not say truly, Gandalf, that you could go withersoever you wished
quicker than I?" He says it twice, but Gandalf does not contradict him either
time.
It pains me to say this, it really does, but I think we have to understand that
Gandalf can transport himself, for lack of a better term.
Gandalf also says that from Lorien, "thence by strange roads I came." There are
no roads stranger than being carried by an eagle, I'll agree, but why would he
cadge now when he was so open about Gwaihir carrying him from Zirakzigil?
He says that, after the Amon Hen incident, he "walked long in dark thought." He
actually has 4 days to get to where they meet in Fangorn. We don't know what or
where the "high place" was, but there are mountains on the western border of
Fangorn, if it was a physical "high place."
If an eagle had left him in Fangorn, it would have to be the one Aragorn sees
on the 11th day (remember that Gandalf saw Treebeard 4 days before they met
him, on the 15th day). That eagle is "high in the air, descending in wide
circles to the earth." That's a hunting eagle, searching the ground for prey or
for information to take back to a wizard, not an eagle carrying a passenger.
I'd say the one Aragorn sees was Gwaihir gathering information about the
capture of the hobbits; he reports to Gandalf in Fangorn that night or the next
morning, and then Legolas sees him flying home from
Fangorn.
