My 4 month old Maine Coon kitten just threw up!?

I have a cat too, and trust me its completely normal for a cat to get sick every so often. If your cat is anything like mine, he probably doesnt chew his food well, and just tends to swallow it whole. That can upset his stomach because it isnt digested well, like you said. If he keeps getting sick with dry food, you may want to try feeding him some wet food, preferrably tuna because it doesnt bother them as much. Or you can use some nutri-cal supplement that comes in a tube, just to make sure he gets all his nutrients if he's getting sick all the time. Trust me its not a big deal, but I'd recommend breaking his food into smaller bits that way he can digest it easier. Hope it helps. :]