A tick-tock book?

I was recently listening to the Slate Double X Gabfest where one of the members described Game Change, the book by John Heilemann and Mark Halperin, as a "tick-tock" of the 2008 campaign.   I had never heard this expression before in reference to a book and I tried to Google it but the only other mention of it I found was also in reference to Game Change on a political blog: http://www.thefeeherytheory.com/2012/03/13/picking-a-vice-president/.   Is this a bit of political lingo or is it a publishing term?   Thanks!