Are the scores in your signature accurate for when you applied for this card?
EDIT: Snipped for posterity: Experian: 713 | Equifax: 712 | TransUnion: 716
Congrats and use it wisely!
I was an AU on Amex at 16 or so, got my first personal card at 19, closed the account myself at 23 and then after ruining my credit in my late 20s I had a SECURED Amex card which I ended up not paying so they used the security deposit to pay it off.
Haven't been able to get back in with Amex since then. Don't do what I did -- manage it well and in 30 years (or less) you will be really thankful for treating it well because they will treat you well!