I don't know what the laws in PA are concerning this, but unless there was some damage done this may be no more than a procedural problem that needs to be addressed within the agency. However, being an arrest, it may not be subject to non-disclosure laws.
You should contact the agency first, and see what they have to say about the matter. if it's money you seek, then go to an attorney (but without damages I doubt there's going to be much there). If it's simply an end to the chatter about the issue, then you need to speak to the agency.
- Carl