Well i've heard my rats hiccup only a few times, probably from too much water or something. What first came to my mind is gas, any food like vegetables, or maybe the seeds etc. that u feed him just may give him gas and he hiccups. If he doesnt seem to be in stress or discomfort or anything like that , he must be just fine. What you could do is go on the interenet, look up information on human hiccups and see what causes them. And if your really concerned, just give your vet a call and talk to them about it, and ask if it could be anything serious.
