I don't know why it being a golden seems so surprising? Goldens (and Labs) due to their huge popularity in this country are grossly being overbred by every Tom, Sue, and Harry, and massive amounts of puppymills breed these breeds.
Which results in Goldens/Labs that are poorly bred and unstable. And of course, any breed of dog can become aggressive/fearful/unstable through poor ownership.
Let me just mention that while working as a groomer I was bit by far more Goldens and Labs than anything else. Except maybe Jack Russells...evil little things! (Just teasing, I promise!)