Why are the posts not in chronological order? I start to comment, then realize the post was 9 days ago. Is it just me?
Not just you, I have posts from months ago in my feed. 
I don’t worry about the timing anymore. I focus on the messages, recovery, service and gratitude😍
It's because they pop up when someone likes them or comments on them. Typically, a bot or a really thirsty dude will come through and comment on every pretty girl's posts, reviving some older ones or even total zombie posts.
Bc that would be too logical 
Hi Basia!
Posts are similar to other platforms in the way a most recent response moves the post to the top. This way, important conversations stay on top of the feed to make sure members did not miss... so the more popular the post is, the more visible it will always be if there is consistent engagement
Happy to help with any other questions you may have.
Have a great Tuesday!
Not just you.....I talk to year old posts as well from time to time 