Even if you've never had an attack of gallbladder trouble, a bunch of small gallstones is more of a problem than one or two big ones. They can lodge in the duct running from gallbladder to intestine (common bile duct), and then you have an acute problem, and treatment and/or surgery is more complicated. Could potentially incapacitate you while flying.
Big stones, not so much -- more time to discuss and decide.
So current advice for multiple small stones, even if no symptoms, is laparoscopic cholecystectomy (that keyhole bit). It's a pretty routine procedure nowadays, and I doubt that it would affect flying, once recovered. (I am not, however, an AME!)