I can think of worse things to happen to a teenager. The way you can tell you're being a good parent is the fact that he asked you at all, rather than sneaking off on his own. He could have asked another teenager who already has their license. Oh boy - I can only imagine what shenanagens that would inspire!
Hang in there, just remember a teenager's job is to be petulant and annoy their parents. They have too many hormones raging not to!