There are several possible reasons your bill may be higher than usual.
1) You used more natural gas this month (usage varies by season)
2) Atlanta Gas Light pass-through charges vary by month and tend to be higher in the winter months
3) If you’re on a variable rate, the rate changes monthly and fluctuations in the market could drive your bill up or down
4) If you recently changed from a fixed rate to a variable rate plan, that will affect your bill amount
Learn more about the charges on your bill here