Adjustment of Status - I-485

I did my interview 16 days ago and-everything went well but the officer gave us white paper that says case must be review. The officer was friendly and even escorted us out after the interview then Made a photo copy of our id with same address. Strange thing happen after he finished our interview. He put two stamps on our file one was black he adjusted the date on the stamp and stamp the file and use another red stamp and printed out the white paper for case must be review. He kept all our documents and pics put it inside our file. My PD is 12/3/2017 interview Feb/18/2020
Our interview letter was form G-56 says we should ask for officer 2 which many people told us it was going to be a straight stoke interview but we got their and waited for 1hr before the IO came out and ask for to come in. We were not separated and he ask us to seat down and take oat. He was just apologizing for keeping us waiting for long time

Anyone have idea what the stamp was for? Because my online still says case must be review. Also after interview he just told me to be checking online for update