We haven't gone to the park, yet. I take him for walks around the block and he was going to doggy daycare from age 4 months to 6 months, but had to stop, because I didn't get him neutered yet. He does great when people come over on Football Sundays with their dogs.
I think what he wanted was to get off the leash and play. Since that's what he does when I normally bring him there.