I'm with CalGal on this one. If the stone's not bothering you, don't worry about getting it taken out. When the time comes (if it comes) you'll know. Depending on the size of the stone, there are certain treatments which have been show to break them, letting them pass. (Some are done with sonic waves, and some acupuncturists say they can help with that.) Most people who have stones (up to 80%, by some estimages) never even know about it because the stones don't cause them problems.
I can only speak for myself. If I had a stone that was not causing any problems and if it was large enough that it would not enter and cause problems in the cystic duct (duct from gallbladder to common bile duct), I'm not sure I would have surgery unless it started producing symptoms. There are many people who have stones for years with no problems what-so-ever.