Slight possibility. If the OP showed a picture it would help. They may have simply used a connector other than copper and cause it to corrode as well. If this is the issue though it would have to be under the soil where the connector was.You probably ought to call a pro on it: if it's corroding, you may have an actual electrical issue that is putting a current on it, and it is corroding through galvanic action. Unless it's right at the coast and wasn't the right kind of rod to begin with, they shouldn't corrode like that..