Oh yes, growling over food, toys, bones or what have you is a dominance behaviour that should be corrected.
We did the same thing as Lissa did, with our Rotti when we first got her. She was a two-year old at that time, a massive dog, so it was a bit intimidating but we knew we had to establish the rules. The day we got her, we gave her a yummy cow bone and let her settle down with it for a while. We took turns approaching her and taking the bone away from her. We corrected her growling in the exact same way and she understood immediately.
I had a problem with her the first time I trimmed her nails. I made her lay down on her side and started with her back paws. I reassured her continually but she still lifted her head and grumbled at me. I gently pushed her muzzle down, held for a second and said “no” sharply. Then continued with the praise & reassurance the instant she submitted. She still doesn’t like nail-trimming but never tried to confront me again. They learn quickly if you make it clear and don’t back down.
She still growls at the vet, though. Some dogs are just dominant-leaning and it can’t be completely erased, but it must be controlled for everyone’s sake.
The dog has to understand that it is at the bottom of the totem pole, period. A lot of problems with biting or other aggressive behaviours would never happen if more people understood that.