Hi. Yes, it's very possible. Human chocolate has several ingredients that make it toxic to dogs, and many varieties also include a sweetener called xylitol, which can cause a severe reaction in dogs. It is very dangerous. I'm pleased she "bounced back", but do try to be more careful in the future.
Unless your dog is HIGHLY allergic or sensitive, a crumb of chocolate is not going to make her sick. Even an 11 pound dog, small though she may be, will not react to a crumb of chocolate.
Theobromine is the substance in chocolate that is toxic to dogs and cats. Different types of chocolate have higher or lower concentrations of theobromine in them, so depending on what type of chocolate it was, some are more dangerous than others.
Bakers chocolate has the highest amounts of theobromine in it and is very dangerous for dogs and cats to eat. Cocoa powder is as toxic as bakers chocolate. Even a piece as small as one ounce can be dangerous for a large dog to eat, and for a small dog a piece that size can be deadly. Dark (semi-sweet) chocolate is the next highest concentration. A one ounce piece in a dog weighing 11 pounds is moderately toxic. Milk chocolate is much milder. A one ounce piece in a dog weighing 11 pounds is only mildly toxic, so if it was milk chocolate and it was only a crumb, then there is practically no danger to your dog. White chocolate isn't chocolate at all, so there is basically no danger to your dog if she eats it.
Symptoms of chocolate toxicity include vomiting, increased body temperature, hyperactivity and hypervigilance, muscle rigidity, rapid breathing, increased heart rate and lowered blood pressure. If your dog experiences any of these, take her to a vet immediately just to be on the safe side.