My new Red Foot Tortoise " Murphy" is getting used to his new home. I have had him now for about 2weeks. He is about 6-7ish inches long. Everytime I go near his enclosure or close enough for him to see me he bobs his head up and down at me. I've read posts where people say that's just them breathing, but I don't think that's it. He only does it when he sees me near him. Is this a territorial thing? Is it normal?