It's quite low chance. Except of low morale, bandits attitude must be also low. And it's still only a chance. That scene is only a small flavor text though.
Ah I see, I'd still like to actually witness it in game at least once, though. :P Lowering bandits' attitude is easy if you just fight them, but lowering the morale is a pain in the ass since it takes like weeks of ingame time, lol. But what I need to do is just enter my home somewhere between I'm assuming 10 PM and 2 AM and the scene should happen?