April,
Yes, that's the way it's supposed to work.
If you're trying to get the total for the book, so you can say 4 of 66... on the last page of the book, create a unique paragraph tag. If you want, you could set up a special text frame for it, but you can also include it in the regular text flow. Set the font to white, so it disappears.
Then, in the component files, replace the <$lastpagenum> variable with a cross reference to the unique tag, and specify the "page" cross ref format.
Cheers,
Art