God randomly attacks Moses at night...Moses wins.

In Exodus 4.18, something rather odd happens after Moses asks his father-in-law for permission to return to Egypt to help his people leave. Jethro allows him to return, and on the trip back Moses stops to spend the night, and then a paragraph falls from heaven onto the page and completely disrupts the well formed plot. Exodus 4.24 reads, "On the way, at a place where they spent the night, the Lord [the same Lord that is helping the Israelites leave Egypt via Moses and Aaron] met him and tried to kill him. But Zipporah took a flint and cut off her son's foreskin, and touched Moses' feet with it and said, 'Truly you are a bridegroom and of blood to me!' so he let him alone. It was then she said, 'A bridegroom of blood by circumcision.' " What?!?
I read this passage four times, each time trying to figure out what I missed, and why God suddenly decided to come down to Earth and go fisticuffs with Moses. I was rather lost, so I consulted the footnotes. "The unmotivated divine assault is made even stranger by it ambiguous use of pronouns: it remains unclear whether Moses or his son is the victim. The juxtaposition with Pharaoh's firstborn son (v.23) suggests that Moses' son may be the one at risk. The episode runs against the larger narrative sequence in which Moses has two sons." Ooooohhhhh ok. What? It seems that even the knowledgeable staff at Harper-Collins was just as confused as I was. I am not sure if this part of the narrative is a gleaming example of the documentary hypothesis, but it definitely seems like it should be. This passage also got me thinking about Frye's first chapter, and metaphor and metonymical language. I tried reading the entire section again, from 4.18 to 4.31 with these thoughts in my head, and I must admit, nothing really helped. One thing from Frye did stick however, when he said, "Perhaps, then, there is no such entity as "the Bible," and what is called "the Bible" may be only a confused and inconsistent jumble of badly established texts." (Frye, xii). We had already talked about the documentary hypothesis in class, and had already experienced it in Genesis' two creation stories, but for me, this example of a divine fist fight really drove it home. I kind of sorta hope we talk about this one in class, cause I would really like to know if anyone has any insight on this strange episode, of if I'm making a mountain out of a molehill.