No, she won't grow out of it, and will likely get worse without intervention. I had a terv who did this as a puppy, and I was able to completely fix it.
Here's what NOT to do - don't take her food away, don't stick your hands in her face while she's eating, don't try to mess with her. These things will all increase anxiety and make her not trust you while she's eating. This causes resource guarding to worsen. Those things are all common things suggested to puppy owners, but they're incorrect and potentially dangerous advice.
What you should do is techniques similar to this. That technique will reduce stress in the puppy leading to less guarding. This book is also a great resource on resource guarding.
It's fixable at 13 weeks, but you need to address it correctly. I would definitely advise getting a trainer involved too, as you should be getting professional advice, not just taking training advice from reddit.
> dematting comb/rake,
Excellent advice! Just a note on this comb, OP, make certain that an undercoat rake does not have blades! Stay away from anything furminator as well, as you don't want to be cutting your tervs top coat. Go for this style.
I also recommend the high velocity dryer, because unless you live in a desert, it'll take hours for your dog to dry and they'll stink again at that point. Plus skin infections can occur when water is trapped against the skin by a tervs thick coat.
My personal favorite shampoo and conditioner is by Isle of Dogs. It's used by the show crowd, so I can guarantee it'll leave your pup soft, clean, and it won't dry out their skin.
If you get one, get this one, it doubles as a costume!