Okay, just to make sure I understand your set up:
The coax comes off your antenna, and immediately passes through a
ground block. The coax then exits the ground block, and enters your house via a roof vent. Meanwhile, the ground wire that is hooked to the grounding block connects to
another ground wire that is connected to the antenna mount. That second ground wire runs down the the exterior of the house and eventually connects to the home's main ground rod.