Going on what you have said in your mail, i would suggest the pup is simply worried about what she is seeing and reacting by being maybe a bit defensive. It could develop if you dont get her well socialised, but you sound as if you have that side in hand :)
Try not to fall into the trap of soothing her or she may feel she is being praised for her reactions. It may be best to either distract her, or even totally ignore her.
Invest in "The Perfect Puppy" by Gwen bailey, as it is a great read and very sensible. Also guides owners into adolescense

Best wishes
Lindsay