They're apparently airing a preview for Season 4 on HBO on Sunday evening at 8:58pmEST, but for the time being, they've released some Vines. The below Vine could maybe be considered a spoiler if you haven't read the books, but since we haven't even met at least one of the characters yet in the show, it's an extremely minor, almost inconsequential spoiler.

Behold, my favorite!

RED VIPER EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!