The problem is that the records that the government can access are more extensive than what a private person can access.
INA § 101(a)(48), the definition of a conviction. It states that:
(A) The term "conviction" means, with respect to an alien, a formal judgment of guilt of the alien entered by a court or, if adjudication of guilt has been withheld, where-
(i) a judge or jury has found the alien guilty or the alien has entered a plea of guilty or nolo contendere or has admitted sufficient facts to warrant a finding of guilt, and
(ii) the Judge has ordered some form of punishment, penalty, or restraint on the alien's liberty to be imposed.
(B) Any reference to a term of imprisonment or a sentence with respect to an offense is deemed to include the period of incarceration or confinement ordered by a court of law regardless of any suspension of the imposition or execution of that imprisonment or sentence in whole or in part.
Because it is such a minor issue that wouldn't normally result in a finding of inadmissibility, the safer thing to do would be to say "yes" in response to that question and provide certified copies of any report and court disposition.
The thing is that while this is a minor issue a may not even be, as you say, a crime, there is a very good chance that it will not have any affect on your process. BUT if you say "no" and it does pop up in their records, then having "lied" about it (that's how they will see it) could end up in a denial. So it may be better to disclose and handle it like that.
Please let me know if you have additional questions and please do not forget to rate my service to you (not the state of the law) as that is the only way that I can get credit for my assistance. Even after you rate the service, I can still answer additional questions for you without additional charge. If you do rate me positively, a bonus is always appreciated. If you would like to request me in the future, just go to http://www.justanswer.com/law/expert-guillermosenmartin/. Thank you!