jeff_duntemann mentioned that he thought he smelled gas down at the back edge of the yard. I had thought it might be due to the storm drains back there, but when I wandered back there with Katie this afternoon after work and smelled gas, I checked the drains and they didn't seem to be the source.So I called the gas company and they sent a man out. His sniffer shows that there's definitely gas back there -- the trick is going to be figuring out where it's coming from.
But at least it's outdoors and well away from the house.