Why would you want to challenge your rejection because of a misdemeanor? The process is so subjective that even if you were rejected for that reason alone you probably wouldn't be told that.
I doubt it'll be a deal breaker, but think of it this way: given two nearly identical applicants, would you rather take the one with or without a criminal record (even if it is a misdemeanor)?
EDIT: Didn't see that it was dismissed. In that case, this won't affect you at all.