Adjustment of Status - I-485

Hi everyone. I’ve been a silent reader on this forum because it’s difficult for me to register but I just troubleshooted it today with the help of a friend and I’m glad I’m in .
My AOS lasted for ten months,my interview was smooth and everything went fine. At first, I got a notification that my case my be reviewed but after 30 mins I got another notification that my card is in production and will be mailed to my address. My interview was 8/16/2018 (Thursday) but today I got two letters one for me and the other for my wife which states the approval of her petition for me and mine stated the approval too, but said they might have me to come do another biometric even though they weren’t certain about it. I just need y’all good people to please help me with answers if I’ll have to go do the biometric or sometimes they send random letter like that and might still receive my card regardless. Your replies will be appreciated . Thanks in advance. Pls feel free to ask me any questions