If the involuntary intake of air is your only symptom, it is nothing to worry about. If it is accompanied by any other respiratory symptom, it would be wise for you to discuss this with your doctor and, perhaps, have a chest X-ray.
With smoking cessation and your recent severe case of the flu, your breathing may be temporarily altered. You do not need to do anything. In time, your breathing pattern will normalize. This may take 3-6 months.