Awarded 3 day Premium upon Registration: Glitch or Luck?

As the topic says. I've read posts about how you usually get it when you've been offline for over a month as a welcome back present, but this was given was the same day I joined (20th Jan 16 - or thereabouts)
Was it a glitch or was it some award for 'being the ___th person to join atWar' or some such, and I just got lucky?

It's not luck, everyone gets 3 days premium upon registration, so not glitch or luck.

Ok thanks