I remember listening to a podcast that mentioned that same fact. However, the context of that conversation was not in a character doing something unexpected, but that the voice of Vin made it more natural for her to be a boy. However, this is not a plot issue. It was in an early writing excuses podcast where Brandon mentioned that his characters never do something unexpected since he is an architect writer. He decides what the character does long before he actually sits down to write, and if during the world building process the character changes the way the plot goes so be it. This change occurs, however, long before the character goes into the canonized version that we need to work off.