Obie Fernandez wrote about some problems he's been running into with respect to story granularity, and Bill de hÓra picked up the thread. This is a subject I've struggled with a number of times, so I'm going to give myself a little free therapy and try and work through some of it here.
If the subdivision is necessary for tracking progress, but all the work will be done within an iteration, then you've dodged another bullet. If, on the other hand, the pieces that make up the minimal marketable feature will be split across two or more iterations, you're facing a new problem. Even if those iterations are within the same release right now you may be reducing your ability to release, to adapt, to change.