Adjustment of Status - I-485

Hi guys, so i finally had my interview yesterday. Everything went rely fast. They didn't ask anything at all other than the normal questions, name, address, phone number etc etc. My husband and I went inside the interview room at 2pm and came out at 2:14. It was really fast!! The officer said he didn't need to ask any questios abput aour marriage since we have 2 kids and he approved my case. He said he was just going to do a background check and that I should expect my card from 2 to 3 weeks. He said the background check takes a day. I checked my case online on uscis case status and it dosen't show any changes it's still in "we scheduled your interview" . Does anyobe know what happens next??why did he have to do another background check???