80 633csi Tappet noise

I have a 80 633csi with 100kmiles on it. I just bought it and the prior
original owner told me the tappets could be adjusted. He never did it
cause the mechanic told him it was not necessary. Never done.
I took the car into the dealer to have the work done (inexpensive)
and the tappets still make noise after warmed up. Is this normal??
It's not real loud but I wouldn't think that one shouldn't hear much of
anything. from under the valve cover if they're adjusted correctly. Am
I too picky?? Also, they adjusted the tappets with the engine cold.
Any thoughts, Fred.