Very doubtful that it was methane from the landfill if your referring to Triple K Landfill which is the only MSW landfill in the area. Maybe theres an old closed one nearby that Im not aware of since Im not familiar with the area. I was at Triple K yesterday to do some sampling and thats an unusual landfill. It perched on the knob and methane migrates upwards whenever possible. The hydroge sulfide is the most logical explanation.