Typical propane usage?

I am questioning my propane usage for the past month. I live in MD, so winters are not that cold compared to other states. From mid November to mid December, I used 108 gallons of propane. The beginning of Jan. I installed a programmable thermostat. We used 104 gallons from mid Dec to mid Jan. My last bill claimed we used 158 gallons I don't understand how I can be using so much. I keep the house at 67 degrees during the morning and early evening. During work hours, the house is at 64 and overnight it is 62. The house was built in 2001, so there is sufficient insulation and we have double-pane windows. My gas oven broke in early Jan., so we have not been using it. The hot water heater is kept at a reasonable temp. I just don't understand. Does anyone have any ideas?