Aw, there is nothing wrong w/ your little fella, he is just too universally attractive for his own good

. Perhaps he rubbed/rolled on something that other dogs are smelling right now. I do think you're very smart to worry about his safety, like you said. I think as long as you keep his leash on and your eyes peeled, hopefully you'll avoid any dogs sneaking up on you. Maybe ask your vet about this too?