I don't know if it's appropriate, but you might ask an MS-X, "How has your view/outlook changed since entering medical school?" If it's a physician, it can be tweaked a little to include how they have changed through pre-med, med, etc. I have yet to be so fortunate to be offered a med-school interview, but I would think of like any interview (or date for that matter). People like to talk about themselves. Eh, but I could be entirely wrong. Who knows. It's better than say, "Nope. Thanks. That was fun, see ya later!"