I haven't had a time yet where I haven't had to log back in if I leave the site. I tried clicking a random thread like someone mentioned in here and I still needed to log back in. Such an odd deal lol.
I has been happening to me on all devices for about a year now. I have to login to post. So it is not just front page for me. This is on both Chrome and IE and it is at home and at work. Also does it on my cell.