Source? I don’t believe that he’s “walked back” from any of the statements in the book.
http://www.cbsnews.com/8301-503544_162-20095591-503544.html
http://blogs.wsj.com/washwire/2011/08/18/perry-is-less-fed-up-over-social-security/
Mind you I agree with Perry’s original beliefs on Social Security, but I don’t need people who want to leaders slinking away from something they beleived in strongly enough that he put it in a book.