I'm too lazy to look this up, but didn't Miles say he heard Juliet say "It worked" from the beyond the grave? She didn't actually say it to Sawyer, did she? Either way, that whole scene by the candy machine included some of that same exchange, (the bit about getting coffee, how "it worked" after they unplugged and plugged in the machine), so I just took it to mean that during her death, she was kind of in between worlds, and Miles was hearing snippets of her after-life conversation. So that comment was just a red herring and no in relation to the atom bomb at all....Just a theory.