Evening Post - Nazgul in the East Emnet Gullies?

I've been playing The Lord of the Rings: The Third Age lately, and this is my third time through the game (haven't played it since last Dec.). I figured I pretty much knew everything about it, as it's a fairly linear game, however I encountered something quite surprising last night: Nazgul in the East Emnet Gullies.

For those who haven't played the game, it's divided into 3 Episodes (one per film) and further divided into 3 areas. The first area of the second Episode is the East Emnet Gullies, which are the hills on the west side of the Argonath that lead into the plains of Rohan. This is close to were Aragorn, Legolas, and Gimili pursued the Uruk Hai at the beginning of The Two Towers.

Anyway, I was going through these hills, helping a Galadhrim Elf find his missing scouts while dealing with bands of Uruk Hai (rather difficult at this point in the game), Orcs, and Wargs, when I entered an Instant Battle and found myself against 3 Ringwraith Shadow Captains; the Nazgul.

My first thought was WTF? There weren't any Nazgul on the eastern borders of Rohan in the films, and my second thought was oh crap, I'm not strong enough to defeat them yet.

This nearly proved true, as all my party save Idrial, the Galadhrim Elf of my party were knocked out. I had to use a cheap (though legit) tactic to defeat two of the Nazgul, then I was able to revive the rest of my party and crush the third.

My characters leveled real good after this battle, I can tell you.

After doing some poking around the net, it seems there are two area in the East Emnet Gullies where you can fight three Nazgul at a time, and also a couple areas where you can fight them (though possibly one at a time) in the upcoming Plains of Rohan.

I just want to get to Helm's Deep and kill many Uruk Hai.