MIMF

I have been asked if my bridges are grounded, and my answer is "to what?".
I sometimes will use single coil mag pickups in my guitar builds, and I have not run across any grounding issues that I can attribute to the strings. But, I just had a heated discussion with a potential buyer so just in case I'm wrong, hopefully somebody here can correct me.

My builds are acoustics, or semi-hollow bodys with solid through necks ( aka Cigar Box style). My bridges are carved of exotic woods, and have a bone saddle and they sit on the soundboard like a mandolin bridge, held by the string tension. The nuts are bone as well. The strings are typical metal wound, and anchor at one end with the tuners, and the ball end is usually a small diameter hole drilled through the tail end of the neck with a piece of bone or leather in place to protect the soundboard.

None of the components are metallic with the exception of the strings themselves and the nickle fretwire in the fretboard. I just received a rather lengthy lecture about "ground loops" and the danger of electric shock from using mag pups without properly grounding the bridge.

What am I suppose to be grounding too? I can't solder a ground wire to my wooden bridge, or the bone saddle. I don't seem to have a buzzing issue and if I did it is usually a badly soldered ground to the jack. Do I have any cause for concern here?

Your customers' concerns are valid. An electric guitar or pickup should always have a string ground. I think that instead of a "leather or bone" thing to protect the soundboard, use a metal piece and solder a wire to it and then the other end to the ground on your output jack.

would a strip of nickel fretwire suffice?
I can inlay it under the string course where the strings would lay across the tail and solder a ground wire to it.
I don't think it would distract that much to the appearance.

Yes, that would work. Just make sure you get a good connection to it, it would work fine.