But mistakes can also happen.
I was replying hypothetically if that kind of mistake happened (nobody realised during the scene that a roll should have been made) and assumed that it was found only later after the scene. If it’s noted right after the event (a player saying ´wait, shouldn’t there be a roll of bluff for that?), I’ll acknowledge and ask for the roll, but if it’s found out much later, before backtracking instantly to correct the mistake, first I ask myself about the consequence of the mistake, what would have happened if the player failed at its roll. If the result would have been trivial, no need to backtrack, just move on and roll with it. So yeah, the player just got an automatic success, but it was not intentionnal, just an honest mistake.