Puppy dominance?

I have a 7 week old miniature schnauzer and I'm really getting concorned she will be aggressive when she is older towards my chihuahua. Whenever my 9 year old teacup chihuahua puts her in her place (when she is trying to play or bite at an inappropriate time) every once in a while the puppy will start growling back, and it doesn't sound like a playful growl. It's a loud, aggressive sounding growl. This really worries me because if she starts trying to be dominate over the alpha when she is big, I do NOT want a fight to break out. She could seriously hurt my chihuahua. I always correct it by putting her on her side and holding her neck and chest with my hands until she becomes submissive (exactly the way ceaser Milan does it, it doesn't hurt her at all). But is this enough? Most of the time when Zoey puts her in her place she doesn't growl or anything, I don't know if she just gets scared or what. Please tell me what you think it is (if you actually know what you are talking about) and if it's something to be concerned about, what should I do about it?