Did HBO reveal major Game of Thrones Season 4 Spoiler about White Walkers?

The most recent episode of Game of Thrones ended with a White Walker turning a baby into a blue-eyed monster simply with simply the touch of its finger. The scene came as a shock to many fans of George R.R. Martin's books and of the TV series, and HBO may have spoiled a major detail about the context of the scene.

HBO wrote the following as part of its Game of Thrones Viewer's Guide after the most recent episode, "Oathkeeper."

"A White Walker claims the baby and rides to a city of ice. The child is presented at an altar, where the Night's King greets the infant and lays a finger on its cheek. The baby's eyes turn White Walker blue."

The guide has since been changed to simply read "a Walker" instead of "Night's King." But just who is the Night's King? A Wiki of Ice and Fire explains:

"According to legend, the Night's King lived during the Age of Heroes, not long after the Wall was complete. He was a fearless warrior, who was named the thirteenth Lord Commander of the Night's Watch. Later he fell in love with a woman "with skin as white as the moon and eyes like blue stars", he chased her and loved her though "her skin was cold as ice", and when he gave his seed to her he gave his soul as well. (Her description matches that of the Others.)

He brought her back to the Nightfort and after the unholy union, he declared himself king and her his queen, and ruled the Nightfort as his own castle for thirteen years. During the dark years of his reign, horrific atrocities were committed, of which tales are still told in the North. It was not until his own brother, the King in the North, and Joramun, the King-Beyond-the-Wall, joined forces that the Night's King was brought down and the Night's Watch freed. After his fall, when it was discovered that he had been sacrificing to the Others (possibly in similar way to Craster), all records of him were destroyed and his very name was forbidden. It is likely this led the lords of the North to forbid the Night's Watch to construct walls at their keeps, ensuring the keeps would always be accessible from the south."

What, if anything, do you think this means for the future of the book and television series? Let us know in the comments below.