How to get my dog to stop growling?

every time we go to put him in his kennel he growls at us. He's trained to go in as soon as we say cage, and he obeys but he gets really pissy about it and makes a big fuss. He's very playful and loving and never bites (he does get quite violent when he has a rawhide or piece of meat he's protecting though. Because of this we never give him rawhides anymore.) but the growling is quite annoying to me, and I'm a bit concerned one day he'll snap. I've read growling while looking directly at you is a dog's way of warning you he will bite you if he has to, which will definitely not fly well if it does come to that. He's a big dog, and could do some damage if he wanted to (though I doubt he ever would.) Suggestions?