I'm sure it could be a really nice and neat job on that ground and all, or that the bolt passes through into a very solid part of the body. But for me personally I would double check that its sanded down to bare metal below the grounding terminal ring. Looks like there is a washer or something below it, maybe this is part of a sleeve that bolt goes into or something, but I would double check that and make sure its good bare metal going into a good piece of the body.
If its a solid ground and good contact on a good bolt then disregard all that, also its probably a good ground if it worked for 7 months without a problem. Hope you can diagnose the problem, if not I am sure you can get it fixed fairly easily. If you bought it new you should still have plenty left on the warranty.