It is more likely that :
1. you have not moved in 2 years therefore your informations you provided matches with the one pulled by Citi.
2. you already have some other version of Citi cards, so you are sort of "pre-approved"
I doubt that...I have been in my new house exactly ONE year now and I had had CITI crds since 1997.
I have a feeling why this happened because I have stopped doing anything with my credit score when it dropped like a ball in SEPT 2008o approx 600. It is back to 800+ so maybe that is why the instant aprovals.
I am just happy that I do not need to go thru the "more info needed" letter route.