Welcome to DST, those of us who changed over this morning at 2 AM. The automatic detect of the time change does not seem to be working with the new rules.
To change your post time, go to your control profile (User CP in purple box at upper left) and select "Change Options". Scroll down and you will find a box that says something like "(GMT -6:00) Eastern Time" or whatever is appropriate to your time zone. Choose the one that is one hour less and remember to click "Save Changes" before you exit. I chose GMT - 5:00 and am now correct.
Note: Below the time listing, is a DST correction box. I've set mine to OFF just in case it decides to change my time again in April as it used to do.