I'm all for being polite, friendly, respectful and all that other good stuff. That said, as nice as many of the tellers that I deal with are, they generally haven't gone out of their way for me that much in terms of setting aside silver or anything else (although I didn't ask for silver specifically, I asked for halves, big dollars and anything else interesting). I'll consider goodies for the tellers at one branch that set aside from CWRs for me, but for whatever reason these CWRs have produced next to nothing so far (maybe one Roosie and a bunch of wheats and random foreign coins; one '64 half in loose halves). But since this is the one branch that actually tries to contact me when they have CWRs, I guess they deserve something for keeping me in mind.
I'm not trying to say that CRHs shouldn't buy treats for tellers - to each his/her own. It's just that unless they are looking out for me, I don't feel any needed to reciprocate. They are friendly and nice to me, but I treat them the same way. The day a teller actually contacts me or sets aside something for me is the day they go on my "treats" list.