Sneezing is a symptom of irritation in the nasal passage. It can occur in response to irritants in the environment such as dust, pollen, cleaning agents (especially carpet treatments) or deodorizers. It also occurs in response to infection of the nasal passage like a "cold." If that is the only symptom he has and his appetite and attitude are good you can watch and see what happens from here, it may resolve on it's own. It can help to use a humidifier or steamy bathroom 15-20 minutes 2-3 times daily as this helps him clear irritants from the surface of his nasal passages.