I know this was a long time ago, but I am having this exact problem now and am disputing with the water company over a bill that is triple my usual bill.
Lightning struck their pump, so they had to switch over to the "old well" while waiting for the replacement pump, which, when it arrived, they installed it and switched is back over. There was clearly air in the lines for a couple days, as the water was cloudy.
We have no leaks (this is a difference of over 12000 gallons!) and nothing was left on. Our usage on the current cycle so far is right back to normal, indicating that something last cycle was an anomaly. Well the ONLY thing that changed was on their end.
Problem is that my neighbor's bill was essentially the same as their usual bill, but there is no explanation other than a large amount of air forced through my pipes that spun up my meter in either a large burst.
If anyone sees this and has an explanation, please post it here or send to my email at snipped-for-privacy@gmail.com