I couldn't believe it either. To investigate this theory, I rewatched the last few minutes of the finale several times to make sure my eyes weren't playing tricks on me. And yes, it definitely looks like the Army of the Dead is shaped like a direwolf head. The direwolf is, of course, the sigil of House Stark, and it seems to be a massive clue that Bran is the Night King. Or at least that the Army of the Dead has some connection to the Starks. In the books, the Night King is a fallen Lord Commander of the Night's Watch, who is rumored to have been a Stark.