It was not.
There's that one ep where everyone in Metropolis turns against him and he's swarmed by people with paperwork... They want to know if he's got a pilot's license, etc. It's mentioned there that he's an "illegal alien," and I don't think it's ever mentioned again.
It's possible that was quietly taken care of sometime after that ep, but it's also possible that people just went back to ignoring it (the same way they ignore his vigilante status, since he was also never sworn in as an agent of the law).
Paul
