I wouldn't make a thing of "disciplining" for the growling - for a three year old I wouldn't call it an alarming behaviour.
Two and three year olds are known for their mercurial mood changes and tantrums. This is because of a range of areas of development all going "full speed" at once. It's like having a tiny teenager who is frustrated by their lack of understanding of what they're feeling, except that they don't like it.
What I *would* do is keep up with what you're doing - asking her about her feelings and brainstorming with her when she does start growling. At three, your daughter is learning to use her expressive language, and this is particularly important to do with how she manages her emotions, both now and in the future. Encouraging her to talk about what is bothering her, rather than ignoring it or punishing for the growling, is the best plan.
_________________
Aspiealidocious.