If it was milk chocolate, you don't have much to worry about at all. Chocolate is more dangerous when it has a higher concentration of cocao-- most of the chocolates people eat as treats have a low concentration of the stuff. The really dangerous chocolates are ones like extra dark baker's chocolate.
I work at an animal hospital, and we've seen dogs who've eaten whole boxes of milk chocolates with no ill effects (except that the owners wanted to bap them for stealing their goodies!)
