Lets just slow down a second, ya'll making a mountain out of a mole hill.

Yes, you should tell them about the misdemeanor that occurred five years ago; no they will not likely care about it, it is a petty offense and the magic numbers are 5 and 10 years. Not like it is a DUI or domestic violence anyway.

As for will it show in a background: highly unlikely. The FBI database is a reference only, the airlines are allowed to cross reference you, but they do not get to look at records and dig through your life. Additionally, TSA will run a background through the NCIC for detailed criminal history, which is as tied in with the FBI reference base, your misdemeanor may have been reported to NCIC depending on the agency that issued the citation.

Best advice, just be honest and tell them you got cited for DD and when they asked for the details tell the truth and it will likely be a non-issue because, who cares at the regionals anyway.