Is First-Class Flying Getting Cheaper?

Back when I used to fly a lot, I always wondered why business class seats were so much more expensive than coach. They weren’t twice as expensive, as you’d expect, they were four times, maybe five times as expensive. Why?
I don’t fly very much anymore so I don’t care as much. However, a few months ago, when I flew to Bogotá, Avianca Airlines offered me a first class, fully-reclining pod seat for $700, compared to $400 for a coach seat. What a bargain! But I figured I had just lucked out with some kind of Avianca deal and thought no more about it.
Today, though, I booked a flight home on American. The coach fare was $587, which is really $617 when you add in my one checked bag. A first-class seat was $694 with free checked bags. When did this start happening? Is it because I booked a flight that was only two days away? Have first/business class seats gotten cheaper? Did I just get lucky? Or what?