It wasn't really a secret, else they wouldn't have gone with that poster. They just realized almost everyone knows he's going to appear this season, so what's the point in hiding it? HBO
Having worked on the show this year i could tell you guys some serious spoilers that would blow your mind but i will refrain
I do happen to known that the dude who plays Hodor is a homosexual and has openly bragged about fisting a guy. Yes hodor fisted a guy... let that sink in.
Btw it's amazing how many people know of plot developments and how little has leaked in comparison. I mean there gotta be dozens of extras alone, let alone all the tech guys.
I guess thats dowm to loyal fans of the show who wouldnt want to spoil anything as pretty much everyone i spoke to who worked on the show were massive fans. We were also made sign papers that forbid us from leaking any information and i guess the majority of us dont want to lose out on our pay cheques or run the risk of not getting to work on the show anymore.