That could be a lot of things. A bad cable. Dirty contact somewhere. Even with humbuckers you can get buzz like that if your amp's ground or power is "dirty". Some amps hiss and buzz with the gain way up. Electrical airwave interference in the room can create a buzz like that. Cables touching, like a speaker or instrument cable running over the amp's power cable, can make a buzz. And of course, single coil pickups naturally buzz like crazy. The little chug you put in there doesn't sound very single coil-ish, but it could with a lot of gain from the amp or with a pedal in front. With a true single coil guitar, shielding the pickup/control cavity and the underside of the pickguard with copper foil and grounding the cavity to the guitar's ground helps kill the buzz. Bottom line, lots of stuff can cause that buzz sound. Fiddle around and see what's causing yours.