As was noted in another thread, there seem to be slight inconsistencies every now and then in the World of Ice and Fire. That's not so strange, as it is a huge project, and keeping everything straight must be difficult after a while, especially when multiple people work on the same project. A second thing to consider, is: is it truly an inconsistency that you spotted, that could potentially be fixed in a second edition/online edition? Or, as happens on occasion in asoiaf, is it intention