Ok so i was plugging my external hardrive (Western Digital 1TB My Book) into the right side USB port. The lights were off so i kinda scanned down the side of my laptop with the USB plug looking for the right hole. I'm wearing headphones and heard interference everytime the plug touched the case. I look down and see arcs of power (sorry im not technical in that department) leaping between the gap of the plug and the side of my MBP. Is this a problem with the laptop or the hardrive or just some freak occurence?