I know a guy that scribes the inside of the cam cover noting that he was in there. You can only trust the dealer's service department as far as the degree that you know the mechanic wrenching on your sickle. Valves are a very easy way for them to skimp. Heck any job that you, as the owner, cannot readily check by looking at something, will usually have the dealer saying, not doing. Thus, Kah'ching Clack clack clack.
If you don't feel comfortable about adjusting the valves yourself, you may feel comfortable with checking the clearances. Do so before and after service. That is the only way you will know that the clearances are within specs. Stealerships usually have a 30 day warranty on service. Ensure the motor is dead cold too.
