Honesty is the best policy?

We get our electric/gas bill from the same place. The first few months I didn't think anything about the fact that it said that we had no gas usage - just figured we weren't using the furnace and maybe the water heater is electric, you know? Well, looking more closely at our last bill, it still said we had not be using any gas...and on our furnace, it says "gas furnace", so of course we had been using it. So I called the company and they have now sent someone out to look at the meter that they think is broken. So now, with my luck we will get backcharged for the last few months. My mom works for a gas company, and I asked her about it. She said that they would calculate an average usage for the time frame and probably give me a bill for about 70% of it since I let them know about it. She also told me even if I wouldn't have said something, it would have caught up with us eventually! So I guess I did the right thing?