The concern we should have is not that North Korea would suddenly launch a preemptive strike on Guam or any other target, but that the conflict escalates to the point that there is a miscalculation on one side or another and missiles or bombs are dropped.

I don't think there's much chance that the North Koreans would attack Guam or any other territory out of the blue. They would only counterattack if they felt existentially threatened. The questions is, At want point will North Korea feel it is threatened enough to make such a strike? We don't know that yet.