Stranger Danger Too Close to Home

I have had the stranger danger talk with my 8 year old son so much that he now recites in the most sarcastic tone he can muster, "I know mom, don't talk to strangers. Don't get close to their car, and never, ever go anywhere with them, EVEN if they offer candy, a puppy or a million dollars."

Perhaps the over protective mom in me has over done it? Could I have, by repeating myself so often, done exactly the opposite of what I intended. I want him to be so scared of being kidnapped, that he wouldn't dare venture too far from my side in a store, and is armed with enough tips that he can avoid being snatched.