I'd eat the chocolate and not worry about it. That cat has licked other things that you touch all the time. As my Peruvian friend said once: "You will not die from it!".
What the fuck is going on here? My cat has his own spot on my plate in which he sits on the table and anythng I put in that area is his to eat, I share my bud with him also, he eats buds, likes shotguns,and at times I make him smoke some catnip when im low. My cat is more human and more well mannered that most that walk on two legs. He fights and he fucks just like cats should and actually fights little dogs too. Fuck the chocolate......My cat says your cat looks like a PUSSY.