If someone tells me that info, I would be appreciative.
Guess it depends on how they come across. If they're professional and polite, that's a plus. If they're unprofessional and rude/condescending that's going to cause problems in trying to do their job.
I dunno ... private detectives tracking me down? To quote Kramer, “I don’t like the sound of that.”
I would too, honestly. If I know I was exposed to a known case, I could isolate and protect my family.