Sounds like EMI/RFI noise in the room you were playing. Could be the socket/power in that room. If it was't gounded well the noise collected from the guitar shielding might not be getting to ground...but since the noise YOU collect is getting to ground when you touch the strings, more likely something is producing noise.

Dimmers? Monitors? Lighting circuits? AC condensors outside? Do some checks and maybe you can eliminate it.