I had basically the same thing happen to me, except I was actually put on disciplinary probation for 4 weeks my sophomore year for being caught drinking, which I'm pretty sure is on my "record" somewhere. Anyway, I reported it on the AMCAS application and wrote a little blurb about it. My pre-med advisor told me to make sure that I wrote about what I'd learned from the experience and not to make excuses or downplay it.
I was really nervous that the probation would be a red flag on my application and that I wouldn't get interviews with it, but I did get interviews and acceptances. I got asked about it at a few of my interviews, but I just explained the facts of what had happened and all of my interviewers were very cool about it, they said that they understood that this happens a lot in college and that I shouldn't be worried about it hurting my chances. So yeah, just tell the truth about it and I think you should be fine!