The way I see it, the prick is just a warning. Usually when a snake bites, it first deliveres a dry bite, a mere defense to scare what it sees as a threat away. Being bitten in this way in a dream can be interpretted in many ways. It could represent merely a fear of snakes that you may have, where just getting pricked is encoumpassed in your fears, and you are left utterly unharmed. This could also be seen very metaphoracly for something that is soon happening in your life, or has happened, something you've been fearing, or dreading, that when it finally happens, is painful, but won't have lasting effects on your life.
