I would keep an eye on him for a couple days. If you see or hear anything else, take him into the vet. Does he normally have trouble with hairballs? I give Kylie the Purina Right bites Hairball formula treats, and those have really cut down on them I also feed her the RC slim mixed with hair and coat but am going to switch her to SD Light Hairball formula when I get this bag finished.
Keep us posted!