
All my GSDs have been just the opposite & if bred & reared correctly there should be no suspicion of strangers. It could well be that the breeder of your puppy did not socialize them properly before you got the puppy
Thank goodness the breed standard was changed to take out the "noted suspicious of strangers"which was added to cover up the poor temperaments that were the norm in the 40's to 60's
You need to work on your dogs socialization if you have guests visiting tell them to totally ignore the puppy & if you allow treats or biscuits get them to hold them in their hands palm up & fingers out streatched as you would a horse & to still ignore the dog Eventually the puppy will associate strangers/visitors with nice things & treats. You might have a lot of work on your hands & please don's allow anyone to force themselves on your dog as that will cause more problems
GSDs are no different from any other dog temperament wise & they should be out going & friendly. In the words of one of the best German GSD breeders & judges Alfred Hahn"There is no such thing as a too friendly GSD"