The latest thinking on black bears is that most attacks don't involve cubs or territorial defense, but a predacious bear that views its victim as a potential food source. These bears typically do follow the victim and hunt him or her down, although it's very rare. The behaviour described in the original post is typical -- the bear is following, circling around, snooping about.

This is in contrast to the grizzly, which although it's much more capable of hunting humans, typically attacks out of territorial behaviour or defense of its cubs.

It's about the opposite of what you would expect, and it's why the usual black bear advice -- "don't bother carrying bear spray, just yell and bang pots and it will run away" -- is irresponsible and incorrect. Most black bears will run away if you bang pots, all right -- but most black bears aren't the ones who will attack and kill you.