Mine was set for somewhere in Europe for the longest time so I just updated it to mountain time a moment ago. After I did that they were still an hour behind (posts at 7:00 would be stamped 6:00).
It must be the DST setting not getting the info from the brower properly, mine's set to "Automatically Detect", but try forcing it on to see if it fixes it.
__________________ Uncertainty is an uncomfortable position.
But certainty is an absurd one.