Grave Digging is classified as any new posts on a thread that has not received any activity within two to three months. There is usually nothing wrong with bumping an old thread unless the thread is about buying or selling a product or service, or about a question that has already been answered correctly.
I say no, because is it really that hard to remember the rule which is above me. Besides there are more invalid gravedigging reports then there is people actually gravedigging threads.