With natural gas prices so low, and with Duke Energy apparantly buying primarily on the "spot" market for residential users, one would expect their rate for January to be lower than it is, although it is admittedly lower than last year.
In reviewing my last Duke bills I would venture that there are overcharges hidden in the new, much higher, customer charge. Would take a rate case to decipher, though.
For the current rate click on "ebills" and go to the last bills.