Same thing happened again today, it was on hold at 70, and when I got home it was down to 65 "conservation" mode. I found the setting mentioned earlier, it was set to "balanced", so I switched it all the way to "comfort". We'll see what happens.
Have you gone to oge.com to the smart hours page? They have instructions and explanations of their thermostats. Maybe it will help explain why it's doing what it's doing, and how you can manually fix it?