Negative Gas Bill

Working through our bills last month we discovered that we had a credit on our gas bill. Now I am not entirely sure where this credit came from but I will NEVER complain when I don't have to pay a bill and felt that it was a blessing from the Lord. Again this month bill time came around and I discovered that we again have a negative gas bill. I think they are just deducting each month from the credit but the credit was worth like 3-4 months of our gas bills. So I think I can look forward to a few more months of negative gas bills. I don't know what we did to deserve that blessing but I am hoping it will happen with some of our other bills!