As you mention, it appeared to be pre-planned, but if you’re looking for what triggered it specifically, Don Eladio telling Hector to get them glasses was pretty clearly code for “it’s time.”
And I’ll go with dramatic license also if you’re wondering why it seemed to take Hector so long just to get the glasses, but for a reason- it gave time for a dramatic and ironic set up to develop as mentioned in your spoiler. Consider Hector choosing that very moment as an exclamation point on comparing the relationship of Walt and Jesse to the relationship of Gus and Max (and to give you more summer homework, to the relationship of Gus and Jesse). For the past 2 seasons especially, this is where the core of the tension of the show has come from.