That's odd. Feast for Crows is book 4, between Storm of Swords and Dance with Dragons. This is from Martin's website:
A Game of Thrones, Bantam Books, 1996
A Clash of Kings, Bantam Books, 1999
A Storm of Swords, Bantam Books, 2000
A Feast for Crows, Bantam Books, 2005
A Dance with Dragons, Bantam Books 2011
The Winds of Winter, forthcoming/Bantam Books
A Dream of Spring, forthcoming/Bantam Books