Rest easy, your chocolate is not a dairy product. The chocolate is fine. The concern with dairy products, and meat, (unless they have very high economic protections for dairy) is the potential of bacteria and disease being transported in the product. This would be more of an issue with Milk and runny products, not an issue with dried, solid, or firm cheeses. Also not an issue are highly processed products like chocolate, cheese crackers, items made with dairy or cheese.
Regarding declaring, I agree with the posters above, you walking through the Green door is stating you have nothing to declare. They can, and do stop people after the doors, and if you have checked a bag, or walked through a portal (you probably did) on the way to immigration, your bag has been at least sniffed and checked bags x-rayed.