I got SSSS on the flight from Toronto to Boston this April. It was a round trip and booked a month earlier, with a few days stay in Boston. So everything looked normal. No idea why I was selected for ssss. I never got SSSS before when I was holding Chinese passport to US. But this trip was the first trip since I changed to Canadian passport traveling to US. So I was wondering if it was the trigger. And I'm also worried does it mean I will receive SSSS in the future for every flight to US?