User blog comment:DaNASCAT/Technical Update: December 11, 2012/@comment-4139585-20121211215806/@comment-452-20121212170346

The easiest solution would be for the server to pass a "currentServerTimestamp" variable for the js to use instead of using your computer's time. (This is what I've always done.)

I don't think the "posted ago" text is dynamic, let's test.
 * (several minutes pass)

I've been staring at "7 minutes ago" on the above comment for a few minutes now - since it's not dynamic, there seems to be no reason for the script to use the current computer time as opposed to the time at time of serving.