Meh, stocks dropped for about 2-3 days (depending on timezone and marketplace, here NASDAQ and the Frankfurter Boerse) for a total of 10-15%, and they are already at 95% of their all-time-high again.
The drop was more an overreaction as the stock is absurdly overpriced (even at half the price I would have a hard time deciding to buy), the whole Tesla stock became a gamble and everybody is quite nervous about the best time to get out (well, I got out too a tad too early :| )
About the fire: I find it quite civilized for the huge amout of energy stored. Tesla did think about the case and made its precautions. As brutal deforming or even cutting (im not sure what happened) the cells is about the equivalent to throwing a lighter in the gas tank ... meh, not much happened. Too bad about the nice car, though.