Just as the title asks. Even if I'm standing on carpet, after the charges of the balloon cause my hair to stick up, my hair slowly goes back down as it loses its charge. Are the extra electrons in my hair slowly moving into the air?
The rubbing produces localized charges sitting on the ballon which is an insulator. These charges induce opposite charges on your hair (coming from the ground) which is not a good insulator depending on your grooming. When the hairs are attracted to the ballon touching it, the charges neutralize each other. If they do not touch and you wait long enough, the ballon also loses the charges by air conduction which depends on humidity or by the small conductivity of rubber itself, if there is a conduction path via your hand over your body.
The key to understanding that effect is that there is no such thing as a perfect insulator. Everything conducts electricity, insulators just have a very high resistance.
Over time, your hair will regain neutrality with respect to your body, and your body will regain neutrality with respect to the ground. It just may take a while. It will take longer if you are in a dry climate and wearing rubber soled shoes. It will take less time if you are in a humid climate, or barefoot. No matter what, it will happen.