No need to perjure yourself. Mention the situation during the interview. This arrest was outside of the statutory period. It might delay your approval, but it is better than getting a denaturalization later on. That would be my take, even if I agree with people saying that this is not relevant to get approved, but hiding it might become relevant later.
I filed a FOIA to USCIS re getting a copy of 1 application and a couple of notices of action
- Thread starter zapper43
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That's what I'm thinking. It was already disclosed, and probably is lurking around in some other papers. Why would the A.O. not write it down on the I-589 app itself? While I was telling her about it I could see her jotting down stuff. Maybe it is indeed on a separate paper. 
I've seen more people getting affected by "hiding" a small matter than by disclosing it. Of course I've seen people getting in big trouble for hiding big matters (i.e. major felonies in the past, or a lady who turned her van on fire with her child inside for insurance fraud purposes and then went to interview a few days after committing the crime) Those big issues came back to haunt them for denaturalization. Anyway, if this is something that there might be a paper trail for it I'd think it is better to disclose it. You can do that during the interview. If you don't disclose it, be mindful of the IO asking you a couple of times the question about have you had any arrests. If he asks you a couple of times the same question it might indicate that he/she has some arrest information in front of her. Anyway, I'd go for disclosing this information voluntarily at the interview. If it is outside of 5 years it shouldn't have any effect. Only issue could be if the IO asks for some proof of arrest, some police report from home country. Hopefully not.
It will also go to supervisor approval which might add a couple of weeks delay on approval.
It will also go to supervisor approval which might add a couple of weeks delay on approval.