The following is a screenshot of Youtube's homepage on January 21, 2008. At the top, there is an advertisement for the Lost Season 5 premiere episode. When you mouse over John Locke's image, some words appear. The large print reads, "We have to go back".

However, if you look closely, you will see smaller, blue print that reads "it was not a dream, it was a memory". What could this mean? Was Locke's dream about Horace actually a memory? Maybe Locke lived on the island as a little kid? You decide.