I am inclined to agree culzean, my wifes GD jazz is now on nearly 101,000 miles and is still as quiet as the day we got it... in my 23yrs of owning honda engined cars (and lots of friends and family) i/we have never adjusted tappets on any of them... as long as the oil is changed regular they usually run forever and do big mileages with no problem, or maybe, me/we have just been lucky perhaps??
Valves can fail due to metal fatigue, the valve, "penny on a stick" will deteriorate due to cyclical metal fatigue, the valve stem will elongate, "neck " or "stretch". The stem of the valve elongating will be seen as the tappet clearance closing towards zero. Such valve failures are rare these days, but were a problem many years ago, the VW air-cooled beetles were well known for such failures, usually the exhaust valve, rarely the inlet valve.
The Honda service schedule may well be to keep an eye on the valves, if the gap is closing below service specification, it prompts the technician for investigation such as a cylinder head lift and valve inspection to avoid a potential valve drop and expensive damage to the engine.