The hit in question occurred in the opening minute of overtime. As Jamie Benn skated into the zone with the puck, Cooke appeared to line up for a hit. Instead, Benn threw his shoulder up and connected with Cooke's head as Cooke slammed on the brakes.
The league isn't going to schedule a hearing with Benn because it considered it defensive contact to the head, according to Mike Russo of the Star-Tribune. The league has a nice video explaining this line of thought online (ironically, Cooke is featured in one of the examples they show). Here's a transcript:
...the reason why none of (the following examples) rose to the level of supplemental discipline was because they were protective and defensive in nature. However, these players did receive a warning that if we noticed a pattern of defensive blows, or if the defensive blow was truly predatorily in nature the DPS may decide to enforce supplemental discipline.
Alright, let's look at the play again and see if we can figure out the league's reasoning. Here's the play in GIF-form.
Without the full context of the play, it certainly looks like a blatant check to the head. Benn's wild elbow gesticulations don't really help his cause. Now let's watch it in real-time.
In real-time, you begin to see why the league is backing off from discipline. They must've decided that since Benn saw Cooke lining up for a big hit, he abandoned the puck and protected himself by hitting Cooke.
Now, whether this is the right conclusion is certainly up for debate (And fans on both sides will undoubtedly do so). Although the fact the league has a built-in excuse for hits to the head is a little unsettling, no?
But in the end, it looks like Benn will escape punishment.