To me this is one of those times when God just decides He is going to show his Almighty power. I mean, really, who was really expecting God to strike Herod down and for him to be eaten by worms and die. I know i wasn't, and my guess is that most of you all weren't expecting it either. God just decided that He had enough of Herod and decided that He would make an example. Just another one of the examples that God choses to show us to make a point that He is the Almighty!