I have not been able to replicate this here on meta, but on my site when I save a new post or message, it is immediately indicated to be 4 minutes old. Tried it also in safe mode, same result. I don’t know how long this has been going on but only noticed it today. I make heavy use of the ninja edit window so this is an unwelcome development! Any suggestions on things to try most welcome.
Sounds like your server time has drifted. If you’ve not got NTP running on your server, it’s probably a good idea to configure it. You can test what your server thinks the time is by running
date from a terminal.