I disagree with the previous post. Firstly, there is no such thing as the 'upper abs' and 'lower abs' - they are one long sheet of muscle. Check the diagram at en.wikipedia.org/wiki/Rectus_abdominis_mus
Secondly, you can't 'spot reduce', and crunches (or any other abdominal exercise for that matter) are ineffective in reducing abdominal fat.
But in answer to the original question, typically the body shifts several times each day between anabolic (building) and catabolic (cutting) states as it digests meals and meets energy demands. When you are running a calorie deficit, it is likely to spend more time in a catabolic state, but anabolic states will likely still happen at some times during the day. So yes, fat can be redeposited.
But I suspect that what you are seeing is really an optical illusion. Where we lose fat from is largely a matter of genetics, and perhaps in your case it is coming off the upper abdominal area first. This is giving a greater visual contrast in the way the upper and lower abdominal areas APPEAR, but my guess is your lower abdominal area isn't actually any bigger than it used to be. It's just that the upper area has gone down faster.