Like others suggested, get a real FICO report. Unlikely that citi didn't pull any reports. In my case for my 2nd Citi card, I think they pulled Experian and I thought that was it but a day later Equifax saw a ding too. Well worth the new card but just better that you're aware of what's being pulled.
That's a staggeringly high CL for someone that has almost no credit! It must've been the annual income that did it, however I saw someone say on here that usually that isn't taken that heavily into consideration. I'm jealous of your high limit