Totally agree with ARizzle...you have shown that you are more mature and are grounded. They don't want to see you experience failure by going the opposite direction + they expect more from you. (but I'll bet you've heard that already)
Because a lot of kids will still make bad decisions and they don't want to see you mess up ur life. It's normal for parents, they are realizing how much freedom you are gaining. My parents were the same way. But the bottom line is because they care about you, no matter how annoying it is.*
Some parents are just happy the way there kids act and throw it in peoples faces. If there kids act bad it might make them look like bad parent. Some disapline there kids for the smalest things hoping that they wont do it again making other parents think they did a good dead. Also grounding some parents feel appreciated that they did a good dead it makes them look good to other parents. I guess grounding is a good dead but only if there kid did something wrong. And when there kid starts datin o man thats a whole new story......Hope this helps!!!