Adjustment of Status - I-485

Hi all, I have followed this forum for a while during my adjustment of status application, and wanted to share my timeline/ask if anybody is in a similar situation to us:

Case received: 02 May 2019
Fingerprint review completed: 23 May 2019
Case is ready to be scheduled for an interview: 03 July 2019
Interview has been scheduled: 06 September 2019
Interview date: 15 October 2019
Interview Was Completed And My Case Must Be Reviewed: 16 October 2019

Our interview was very straightforward, probably lasted 15 minutes in total. I handed over my I-693, an updated I-94 and originals of our documents. I answered the Yes/No questions, and then my spouse and I were asked the same questions:

1. Name
2. Spouse name
3. Address
4. Date of marriage
5. Date of daughters birthday

We exchanged a few pleasantries, but overall officer was just very professional. At the end of the interview, the officer just said that we would be notified within 120 days of a decision.

We have a very straightforward case (I think): Joint owned property, joint finances (for over 9 years), married for over 6 years, 2 year old daughter, no convictions etc. I have to say I was expecting to be approved on the spot, but next day status changed to case must be reviewed.

Has anybody had a similar situation with a straightforward case? I figured if they had any doubts over anything they would have explored it a bit more during the interview, but I could be mistaken?

Thanks!