I just entered the states the first time using GE and got the splendid X. CBP officer did not know why either, but was absolutely more friendlier as I got escorted to the citizen line rather than the alien line. I still felt the 'breeze through' feeling but getting the X was not a bright start after all
Did anyone have this experience before too? My speculations for reasons is as follows:
1) I was on an F1 visa (for those that know, it might be that I-20 check is mandatory which essentially means I'll get an X every time...sigh)
2) My flight number origin did not match with my 'trip origin' (I was on a 2-leg journey)
3) Random pot luck???