Lol Aww!
Well... "sometimes the diaphragm becomes irritated. When this happens, it pulls down in a jerky way, which makes you suck air into your throat suddenly. When the air rushing in hits your voice box, you're left with a big hiccup!! Some things that irritate the diaphragm are eating too quickly or too much, or feeling nervous or excited"
So perhaps he is really excited by his new found food and eating too fast or too much? Maybe try helping him slow down a bit or offer less and see if that helps?
Just my 2 cents! HTH
Zoey