Adjustment of Status - I-485

hello
i had a question ....my case status is stuck in on may 22 we have scheduled an interview you should recieve a leter etc....
i recieved the leter 2 weeks after that and had my interview i485 on june 26......the interview went well it was mainly question from the form ... and the the IO told us we should recieve a letter letting us know if we are aproved or if they need something else....but my case status until today has not changed from the may 22 posting interview was schedule.......is this normal?? what should i expect???...by the waywe have already have the I130 aproved prior to the interview.,,,,,would apreciate anyone else that has been going thru this if they could share please ..thank you in advance