I offer and use my credentials at the start of any course I teach as an example of what to look for in a licence and medical.
I'm checking theirs - so I suppose its only fair that they can check mine. A copy of my approval is on the wall in plain view for all to see - so why should I get upset if anyone asks to see it?
I have for some time now encouraged my student FI's to offer theirs as well in their instructing careers.
DD