Actually one of the books written about that incident, "Command and Control," has a lot of interesting detail about the different types of warhead fusing scheme

Actually one of the books written about that incident, "Command and Control," has a lot of interesting detail about the different types of warhead fusing schemes that were implemented at various times. I can't remember which fusing system was on that warhead (though the book describes it in detail) but I think it was one of the more sophisticated kinds than the simple "one point safety" fuses and that the warhead was basically never in danger of exploding.