I live less than 2 miles from a road very similiar to the one you describe except that it's twice as steep (1000' in 1 mile) and it does have two lanes. I drive the road at least twice daily (sometimes more on those annoying weekends!) and I rarely see cyclists even though every local cyclist I've ever met knows of it. Occasionally I see someone trying to ascend the road and usually they are pulled off to the side and standing next to their bikes. It's > 18% grade in some spots! Until a few weeks ago, I'd never seen anyone descending it.

I was on my way home (it was daylight) and there was a cyclist turning down this road directly in front of me. I noted that he was dressed like he knew what he was doing and I had my fingers crossed that he wasn't a poser. He wasn't. He knew what he was doing. He took the lane the entire way down the hill and I found myself glad for him and cyclist/car relations that I was the person directly behind him. I was happy to follow at a safe distance and I had no intention of ever attempting to pass him. Of course, it helped that he was doing about the same speed that is safe for a car, so I did not feel like I was hindered anyway. Another driver might have wanted to pass him though, purely based on the fact that he was on a bike and not in a car. As soon as we got to the valley, he pulled right and let me pass and I gave him a little wave.

Anyway, my point is that I totally get being surprised by your own feeling of annoyance at another cyclist, but like others are trying to point out...your annoyance might have been misplaced in this situation. It does sound like she was doing the right thing for her own safety. I'm sure it didn't help already knowing that she wasn't the friendliest of sorts from your previous engagement. That probably would have colored my view of the situation had I been in your shoes.