WHY ME!!!!!!! They didn't tell me!!!

I was registered when arrived to US but I wasn't born in any of those countries. What are the criterias they look for? Is that a secret they don't want to reveal? Will I be requiered now to register every time I come to the States?

I was registered when arrived to US but I wasn't born in any of those countries. What are the criterias they look for? Is that a secret they don't want to reveal? Will I be requiered now to register every time I come to the States?