I haven't really noticed it, BUT on the other hand i haven't tried killing a shopkeeper and see if his/hers relative comes in and finishes the quest etc. etc. And have quests after Questlines. Closest i've got to was with Nazir in Dark Brotherhood Sanctuary, when he was giving me contracts after contracts. That and the quests.

So is it really in the game? Anybody witnessed it? I'm just curious

Radiant Story = Radiant AI. The lesson is that when Todd Howard says "Radiant", you can disregard what he's saying as 95% lying. Of course, the rest of the time, it's about 50% lying.