When data drive pages are enabled, include a check-box in the page tab of Export Map to pdf so that the current page layout is exported and not the currently selected data driven page.
Currently, if you have data driven pages enabled and you need to slightly modify the page layout (pan or zoom), the export map function won't honor the page layout changes you have made. Rather, it defaults back to the shape and extent of the current data driven page that you are on. This is most likely by design but there should be a check box in the Export Map command to override the data driven pages and export out what's currently on the page layout.
I promoted your idea, but I thought all you had to do to fix this was hit the refresh button on the data driven pages toolbar once you change the scale?
