I have just got back from a long walk in the parks and my dog stayed with me despite other dogs  being around and if you had known him when he was younger you would know that this is a major achievement that I have worked hard for. anyway, back on lead we went to the park cafe and i saw 2 adolescent GSDs on lead so we wandered over to say hello, this was all done in a controlled manor and my dog was calm and the other 2 due to their age very bouncy and noisy as you would expect, after a minute or two  I felt rather than heard an vibration up the lead which i can only assume was my dog growling, i called him to me and put 6 feet between us all and then we went our seperate ways. I have never heard him growl before, only that silly play growl when hes got a stick etc. it seems he has gone from playful youngster to grumpy old man over night. I posted the other day about him not seeming to like puppys much, should I be concerned about this?

On the basis of one incident, no, I wouldn't be overly concerned. In fact he seems to have behaved well given the pain in the wotsit that adolescents can be! I'm not one for reading too much into things that haven't developed into a pattern of behaviour especially when no harm was done.

If the youngsters were very boisterous, then it sounds to me like he was behaving just as he should - politely warning them not to overdo it.  My girl is one of the dog-friendliest dogs you could ever meet - but she does warn other dogs when they push their luck, with a little growl like you described.  It's perfectly normal - I suppose you could liken it to a raised voice with people when politely asking someone to stop whatever's bugging you doesn't work.  I wouldn't be worried.

oh thanks huge sigh of relief