Hit from behind very slightly no damage to either car police was not called is there a claim?

Yes, you would be wise (and your policy contract requires) to report this to your company so they can investigate, and officially get from the other driver they are not injured and there is no damage. I have seen these types of claims many times come back and 'bite' hard. Two months down the line the insured gets an attorney rep letter, claiming both injury and damages. By that time much evidence can be lost. For your own protection report the claim.