Yes, don't think twice if you believe it is a current and not a freaky thing with your cut. Get rid of it as it could cause a fire. I wonder if there is a safe way with a multimeter to check for current on the tank, like touching one electrode in the tank and another to house ground or something?
It might not be tripping because it might be downstream from the AC power input on the heater. The heater may convert AC to DC to actually power the element and perhaps that is what is leaking.
I've determined that aquarium heaters are perhaps the most unreliable piece of aquarium equipment in fishkeeping and also the most dangerous. I've had two highly rated COBALTS that proceeded to set themselves to max 96 degrees and get stuck there (could never change them after I discovered the issue). One killed my whole colony of shrimp as a result. I've since moved to a new strategy and use two underrated heaters, one of which can't heat the whole tank. That way in case one heater goes crazy it can't do too much damage. I then hooked those two heaters up to an InkBird 306A temp controller that will shut them both down if temps go too high. It also wifi's current temp and alerts to me through the app. Never trust aquarium heaters, I don't think there is a proven vendor out there.