for most hondas, the ecu calibrates for rich/lean based on data from the o2 sensor.
if it hasn't been recently replaced with a new one, i'd do it now. just because it isn't throwing a code doesn't mean it isn't on its way out.
if you were inclined to do a tune-up, i'd do the following:
air filter
spark plugs
fuel filter
distributor cap/rotor
stock injectors? may be replace them with known good ones temporarily

finally, when the motor is switched to the larger cam lobes, it is sucking down fuel.
i might lay off 'spirited' driving for long enough to see if it makes a difference.