Does this mean my husband is a felon?

My husband was arrested one day when he was 19 (thirteen years ago) and was charged with three things: 1) possession of a controlled substance, 2) possession with intent to sell/del controlled substance, and 3) use or possession of drug paraphanelia. He said some or all of them were felony charges.

He is trying to get a job that does a comprehensive background check and on the application stated he's never been convicted of a crime (they asked about "convicted" not "arrested" or "charged"). He found his old paperwork and some information online and it states the following information for all three of the charges:
STATUS--"Disposed"
PLEA--"X Plea: Not Guilty-Not used anymore."
DISPOSITION--"PP: Nolle Prosequi"

He said this information was supposed to be expunged, whatever that means. I'm not sure either of us know. He did serve probation, so I'm thinking he was convicted of something, right? This job puts him through a rigorous employment process and we'd just like to have a heads-up...he's made it through a series of interviews and tests, and we're wondering if when it comes down to it this thing is going to come back to haunt him. This is his last step before he actually gets the job.

He has a voter's registration card, for what it's worth, I thought if someone had a felony he couldn't vote. I just learned tonight that he's never actually used it, though, so maybe anyone can obtain a card but they block felons' votes from counting? Of course they weren't his drugs, but that's what they all say. We would really appreciate any feedback.

[Law200]

You may call the clerk of the court and/or the DA that was involved to check the status...if you have any problems let us know.