I normally "button up" about it. figgering what they don't know won't hurt'em...or upset'em but i totally understand where you are coming from and have thought the same thing. It's there house, they 'should' know. but if i can go all day/night there and they never know, then nobody got upset or worried unnecessarily.
and it may depend on the person as well. are they a staunch democrat or anti-gunner? then i definitely would not tell'em cuz i prolly would not like what they'd ask me to do with it .