I'm one of the "better safe than sorry" type of brewers, so personally I would allow it to climb back to the mid-high 60s for a week to see if the yeast find any residual sugar. Shouldn't have any negative side effects other than a longer wait, but its better than bottle bombs or perhaps diacetly. The yeast are dormant so do allow a little extra time for them to wake up, don't expect the beer to hit 68 and the yeast to start eating away. 1.012 is right near 1.011 obviously, but you never know. Maybe you mashed lower than you thought and it could climb even further down...like I said, better safe than sorry.
Cheers