He sounds both under-fed and under-socialized, and with some patience & more appropriate sized meals, he'll probably out-grow it.
One more thing IF the issue continues: have his stool checked for parasites. When snakes are "sharing" their meals with intestinal worms (from eating live prey), they'll
be ravenous all the time since they aren't actually getting all the food for themselves. Just a thought...if it continues...Pay attention to how fast he digests his
meals...if parasites are helping, his digestion might be faster than normal, as a tip-off.