That all sounds a lot like how mine went. It was off when I bought it, but on by the time I got it home. Then it started coming on from time to time. Now it pretty much never turns off. I think every once in a while, it will be off for the first few minutes of my drive, but it never seems to make it out of the neighborhood, now.
I, like many others, don't really miss it, though. It's an annoying red light on my dash, and I guess there are some ways to fix it, now -- I'm especially excited about the Durango find! -- but if I'm going to fix that, I also need to fix the master cylinder reservoir... and if I'm doing that, I might as well put in braided brake lines... and if I'm doing that, then I might as well....
You get the idea.
I haven't been able to convince myself to do a full break overhaul, yet. That, and I've never bled an ABS system, so I have no idea how that is done.