That is worrisome, but you've only had her for a couple days so hopefully with love and patience she'll overcome it.
How are you petting her? Are you reaching over her, to pet her or petting her head? Can you give a bit more of a description on what is happening when she snaps at you?
How are you working on the resource guarding? If you are "claiming" what she's guarding then you'll erode what trust she may have in you since you are "stealing" what she has.
http://www.dogforum.com/training-be...guarding-causes-prevention-modification-7511/
It's hard to advise you without knowing more of what's going on.
A few tips I can give is to let her come to you for attention. When she does so pet her a few times, then stop. Let her ask for more attention.
Don't pet her head yet, wait to do that until she's more comfortable with y'all.
Don't reach over her to pet her. Come at her from the side.
What's her body language when she's "asking for a belly rub"? My dog seemingly solicits belly rubs from strangers, but he does NOT want his belly pet. If you look at his body language he's turned away from the person, his tail is tucked, and he's lip licking (tongue flicking). All of that is fear based, appeasement behavior, his way of saying please don't hurt me, please leave me alone. If your dog is looking like that then don't pet her.
If after a few days she's still snapping I'd call in a good, positive reinforcement behaviorist. You can find one here
http://www.dogforum.com/training-be...ainer-behavior-consultant-behaviorist-113946/
“Three days, three weeks, three months.” That’s the mantra of many dog trainers and behaviorists, when welcoming a new dog into their household. The “magic of threes” is especially relevant when adopting an adolescent or adult dog into your home. Dogs, especially non-puppies, are often in a bit of shock for the first three days in a new home, and don’t show you too much about who they are until they’ve been there a few days. After three weeks many dogs have settled in such that they behave as though they feel like they are “home” now, but don’t fit into your routine until about three months have gone by. The number three has another relevance to new dogs: See below for the three ways we most confuse new dogs, and how to prevent it. - See more at:
Three Ways to Confuse a New Dog
“Three days, three weeks, three months.” That’s the mantra of many dog trainers and behaviorists, when welcoming a new dog into their household. The “magic of threes” is especially relevant when adopting an adolescent or adult dog into your home. Dogs, especially non-puppies, are often in a bit of shock for the first three days in a new home, and don’t show you too much about who they are until they’ve been there a few days. After three weeks many dogs have settled in such that they behave as though they feel like they are “home” now, but don’t fit into your routine until about three months have gone by. The number three has another relevance to new dogs: See below for the three ways we most confuse new dogs, and how to prevent it. - See more at:
Three Ways to Confuse a New Dog