According to the League, Johansson "extends his body unnecessarily upward and makes Hickey's head the main point of contact". See the rest of the disciplinary video below:
Considering Johansson has never been suspended before (and in fact has barely been penalized over the course of his career), and considering that Hickey wasn't injured on the play, this is a pretty harsh punishment doled out by the NHL. Perhaps a clear message - at least until the next time there's an illegal hit - that headshots are not being tolerated.
So... right call, or not?