Honestly, I would. If this whole god-foresaken med shool process has taught me anything, it's that playing it safe is probably the best bet.
All ethical issues aside, if your future medical school discovered that you had an unreported misdemeanor after you were accepted/matriculated, the consequences could be pretty dire. Additionally, I've heard stories where people have owned up to past misdemeanors and still gotten into medical school successfully. The misdemeanor itself doesn't have to be a kiss of death for your chances of becoming a doc, but getting caught lying about it might be.
For what it's worth, I had a (super dumb) misdemeanor. I received a speeding ticket for going <10mph over in a state that considers speeding tickets misdemeanors...six years before I applied. Because I was living out-of-state at the time, I called their local courthouse and learned that it was so minor that it may not even appear on my record, but I still reported it for integity's sake. It came up in one interview, but not in a way where I feel like it threatened my chances of getting into med school at all. I was ultimately accepted to the only school that even asked about it haha. Even though it felt ridiculous to report it, I strongly believe that being transparent about it was the right call. For this reason, I would encourage you to do the same.