Trend of wbc....Decreasing from a high of 9.6 on 3/24/10 to now 5.5 on 5/16/12....Is there some worrying aspect to this...No correlated symptoms?

Tx the pt, not the # The numbers you present, don't mean much to a physician because it lacks clinical context- why was the test done in the first place? Are you on meds that can affect your WBC counts? Unless the clinical aspects are described, it will be difficult for any doctor to answer your question ina meaningful way.
Lab values. Why did you have WBC count done, if you did not have any symptoms? Lab values need to be evaluated in conjunction with other findings. If there are no symptoms you should discuss it with your doctor at the next visit.
Not likely. This depends on how you were feeling each time you got tested. I would thinnk the first reading (9.6) would indicate that you had a possuible infection, as the WBC is borderline high. The last one (5.5) is actually normal, indicating nothing apparently wrong. If it goes down to below normal, more tests might be needed, but right now, with no symptoms, there seems to be no problem.