Assumpta is the Hairball Queen. :roll: No matter how much I groom her, she still tends to get them very easily, always has. The vaseline or prepared hairball gels can help to move it through his intestines, and sometimes just the hacking dislodges the hairball so the cat can eliminate it. Does he seem constipated? Or are you noticing a larger-than-normal amount of hair in his stools?
Has Radar ever had hairballs before? It can be difficult to distinguish between a hairball hack and a cough. If it's been going on for a while and he's not producing a hairball, you might consider a visit to the vet, both to ensure that he doesn't have a hairball blocking his intestinal tract and to rule out the possibility that it may actually be a cough. I took Assumpta in a couple of weeks ago after a few days of non-productive hacking, and the vet and I both thought it was a cough and started her on antibiotics to rule out infection. Several days later, she brought up an enormous hairball, and the hacking stopped

<sigh>...but I was concerned that she was having an uncharacteristic difficulty (usually she yaks them right up, usually in my work boots), so I don't regret taking her in.
If you're concerned, if it continues without producing anything, or if Radar experiences constipation or lack of appetite, or symptoms of respiratory problems, by all means call your vet. But trying the vaseline treatment certainly might help him if he does have a hairball issue.