I've noticed some very minor resource guarding with my puppy and I want to nip it in the bud. She's a 12 month old 80 pound lab mix. I've noticed her guarding only 3-4 times. It's only with my older dog - never with me. She's guarded the water bowl when she's really thirsty and one of her kongs of peanut butter. The behavior was growling. She's typically very submissive to my older dog but I don't want this to become an issue. Advice?