LOL...hey stegosaupus, in my experience the only folks who ever think of stuff like DUI's and such are the folks for whom they have become a matter of routine. That said, comments like the one you mention end up saying a lot more about the person making them than they ever do about you.
In truth, most people wouldn't even think about that when they see someone riding a bike. The feedback that I typically get is that their first thought upon seeing me is that it sure looks like I am having fun!