I don't understand why people so often think that a dog must show exuberant affection towards strangers to be a good dog.
Today at petsmart, a gentleman said hi to Elsie, she sniffed his hand, smiled, wagged her tail, and went back to the heel position (and I was super proud of her; that's exactly the calm, polite response to interaction with strangers I want--she got a cookie and a 'good girl'). He then followed us around the store trying to get her to be friends with him. It's okay man, she's just one dog--don't let this shatter your self-esteem.
PS: thanks boyfriend for body blocking and letting Zobby jump all over him as a distraction. Elsie and I super appreciate it.