They have to see it because I don't have a CCW permit
The only time I carry is when going to the shooting range and that's because I live in a state with no laws against open carry and go to a (strange?) shooting range with odd rules (if you're shooting a pistol it has to be carried holstered, openly).
Still good info for this thread though.
Although I think even if I was carrying concealed I'd still feel this way. If some guy tackles me I'd be worried he'd feel the gun and grab it. Same way when I carry a concealed knife. Maybe it's just my paranoia. I also feel slightly more responsible for my safety and those around me.