Today, I noticed I was logged out of my Binance app, and this is strange to me because I have not been logged out for quite a long time.
This obviously is the reason why they've logged you out because if there's nothing like this, someone else might just get access to your account and easily bypass security checks without being caught. Imidiately I saw this thread, I went right away to my binance to check for similar thing and so far, nothing has changed.
As long as there's no indication that your account has been logged into through another device or an action that is not done by you has been carried out through your account, there's no point for alarm because your account is safe. To an extent, I even prefer the way binance does her security check because it helps you stay protected from external attacks. Sometimes, you might get too comfortable auto logging into your account that you forget your security pass. Occasionally logging out like this is rather for the better rather than a threat.