I happened to go through this type of boarding pass several times, I wondered why i am being screened additionally. But it never took more than 5 minutes for the screening, TSA checked my backback physically and some body searching and few random questions about myself - thats it.

But later I found out that i got that code on my ticket because I was buying my airticket under student discount. Later, i bought my ticket normally and there was no code at all.