Surely you jest.
My understanding is that this is not at all uncommon. It is considered a professional courtesy and can come in real handy if, say, OP calls his local police department and asks about "Agent Smith".
Most LEAs and LEOs will take something like this at least semi seriously because, unfortunately, many criminals are not above pretending to be agents/officers/etc in order to gain access into people's homes to commit acts that would probably get me banned from THR if I typed them out. Or simply to case homes for later burglary.
A simple call to local LE (or the local office of the department in question) for verification purposes is totally reasonable.