Thanks for the advice everyone. Well, I decided I'm going to take him for a walk every day and have at least one stranger give him a treat. I went on a walk today and had 4 people give him treats. The first person was a young boy, and Nebo was friendly with him. The second was a middle aged woman and a young man, Nebo was very skittish with the man. He will go up to them and take treats, just very cautiously. The man did bend down and talk nicely with him. The fourth was another woman and he was ok with her. Good news was no growling/barking or anything like that (honestly that shocked me when he did that at Petsmart!)

Quick question though, does he act like that when he's off leash as well or is it only when he's on leash?
It seems to be only when he's on leash...