OP, I don't have very much experience when it comes to strangers entering my yard, so although I've had many GSDs, this had only happened to me once. Your dog isn't even 2 years old, and when my incident occured my dog was just over a year. My dog came to work with me every day, and he was very well socialized. But when the person entered my property, my dog reacted that same way yours did. Hackles, barking, rushing up (I won't say lunging, because he wasn't jumping) and I wasn't upset that he did it. I was very upset that someone would enter my property unannounced though! This dog eventually became a Therapy Dog, so he obviously liked people. But to just walk into his yard and expect him to be the friendly dog that he was on visits? That's one of the reasons I prefer a GSD, to discriminate between a social visit and an intruder. Intruder, as in "intrusion", as in, "What the heck are you doing in my yard?" I'd get a lock too.
ETA: By the time this dog matured, he could enjoy sitting on the porch and watch the world go by. He didn't run down the driveway barking at people when they came by, he sat where he was. But he did treat the front area entirely different from 'his own back yard.'
Last edited by Blanketback; 11-03-2012 at 12:58 PM.