I agree with Sandie. It sounds like he is marking the food as his, and then trying to cover it to protect it from other animals (real or imagined).
In the wild, when a cat finds a food source, he'll eat a bit, then cover it up to mask the smell so other animals won't find/eat it. Additionally, cats have scent glands in their paws that release an odor which is imperceptable to humans but quite smelly to other cats. When they go through the motions to cover up the food, their paws are leaving their scent all around the area where their food is located. Some will even spray around the area as well to mark that little patch where their food is buried.
In my mind, this sounds a lot like instinctual territorial behavior and probably isn't something you should worry about - however, and this is a big however, advice you get from total strangers on the internet is not now, nor has it ever been a reliable substitute for sound veterinary advice. If you are at all uncomfortable about this behavior, or you feel in your heart there is another problem, don't hesitate to contact your vet.
My continued best to you,