I know people who are in their 30's that wear that stuff, so yea its fine! If you want to create a more 'adult' look, mix some AE with Ralph Lauren, Lacoste, Banana Republic and GAP. Go for similar styles, dress stuff up a bit. Maybe get a nice wrist watch to wear with your stuff :)
Your clothing is appropriate for a guy in college. Out of college, I can't really think of what a guy should wear. I like guys in jeans and plain t-shirts, and I can't think of any place he *should* buy his clothes.