Nervous springer

[applegate79]

Hi I have a 3 year old springer, he has always been a bit anxious about certain things in life. We have 3dc and he is very happy at home, doesn't mind loud noises and noisy children, in fact he likes nothing more than being with us all.
He is nervous with other dogs, another dog went for him when he was about 6 months - no injuries but he was very distressed and since then he is nervous around dogs he doesn't know. He is happy walking with dogs he knows and being gently sniffed by ones he doesn't but when dogs bound up to him off lead wanting to play he cringes, tail between his legs and looks incredibly uncomfortable with the situation. He has never reacted aggressively or growled, but is very obviously uncomfortable and anxious.
He is very ball orientated and I can distract him with one but the minute another dog comes up to him he will drop it and dash back to me. This is not in itself a problem as I always ask other owners to recall their dogs if they are 'in his space' and explain that whilst their dog may 'only want to play' mine doesn't but is just a bit of background to his temperament.
The issue is that he has started lightly growling if adults he doesn't know come into the house is I've just had some food shopping delivered and he growled at the delivery lady. He looks uncomfortable and nervous, slightly crouched and whilst barking/growling quietly was standing back and wouldn't approach (tail also wagging though). I asked him to go to his bed which he did and then he sat quietly watching.
So what should I do in these situations? Completely ignore him? Get the visiting person to give him a treat? Shut him away?
This is a new thing and I want to nip it in the bud if I can but I also want to make him feel more comfortable about life in general.
Any ideas?

[applegate79]

Sorry should have said 'this is just a bit if background to his temperament '!