Clunking Commodore

Can you please tell me if there are any adjustments that can be made to ensure smooth changes in the four-speed automatic transmissions fitted to VZ Commodores? I have noticed on regular occasions a light, but abrupt 'clunk' when the transmission shifts both up or down between second and third gears. It is apparent mostly when accelerating up to 50-60 km/h. Compared to the other seamless gear changes, there seems to be a slight hesitation before the next gear is taken up. The dealer I bought it from told me there was nothing wrong with it, that it was normal, but I'm not satisfied and I'm thinking of taking it to an auto trans specialist. Is this a good idea or should I just turn the radio up?