So you've already PLUGGED it, but I'd *strongly* recommend a PATCH if it happens again. Patches are *significantly* more reliable (who wants a repeat problem?), and frankly therefore safer, too. The "safer" part becomes even more important if you have a wife and kids using the car.
Keep in mind that even if you don't have an explosive blowout from a failed plug (i.e. you just have a fast leak), there's a safety issue with having to drive on a flat tire for a short distance until you can pull over (especially on the highway), and another safety issue with being on the side of a busy road or highway as you try to change the flat or otherwise take care of the car.
The only disadvantage of patches is that they of course require that the tire be removed from the rim, and most people don't have the equipment to do that at home. All of the major tire shops around me will do patches for FREE on tires that you bought from them (and re-balance them for free). Some will even do free patches on new car factory tires (such as yours) if you've been a customer of that tire shop in the past (they want to keep your business).
Oh yeah... after plugging, there's a chance that you'll find you need to have the tire re-balanced.
One last thing... I don't know this for a fact, because I've never tried it myself, but some people say that once you've had a PLUG fail, that spot can't be PATCHED. I rather doubt this, because as long as you could completely remove the crappy goo of the failed plug inside the tire, I think you should be able to get a patch to adhere OK.