OK, maybe this is easily answered because I'm not understanding how Guarded is supposed to work, but...I've been playing Guarded like this:

Put the Guarded card in the staging area and draw a card to 'guard' it. Then if the location, enemy or treachery that's guarding it is removed then it stays open in the staging area.

So, that might be wrong...but, if it isn't, what do you do if you draw a Signs of Gollum and then another Signs of Gollum? I had 3 in a row and then a treachery...so I was like...

You were playing it correctly. In the case of getting several Guarded cards in a row, you will have to reveal a card to guard each one. The first 2-player game I played with Hunt for Gollum started in disaster because all four clues were at the top, so our game started with four objectives being guarded by four other cards.

"If another objective card comes up
while attaching a card for the guarded keyword, place
the second objective in the staging area, and use the
next card of the encounter deck to fulfill the original
keyword effect." (p. 24)

So I see Signs, draw for it, Signs, still drawing, Signs, still drawing, Treachery. Attach that to the first Signs. Then do the same for the other two Signs until each gets a guard.

That's exactly right. It can be pretty brutal if you have an unlucky shuffle.