Has rage ever been associated with excessive hydrocodone?

Yes. Many people with any addiction will have negative emotions such as rage, this may be while they are intoxicated on the drug or when they are in a withdrawal state needing the drug, the later being the most likely cause with opiates such as hydrocodone. They may as well have an underlying psychiatric diagnosis such as bipolar disorder which could cause extreme mood states.
Yes it has! Irritability, anger and even severe rage is not an unusual side effect to hydrocodone. That medicatioin should never be taken without close supervision by a licensed physician and any side effects reported immediately to that physician.
It may be. The side effects of excessive hydrocodone use do not generally include rage. Patients with rage often have a dual diagnosis, meaning addiction combined with other mental disorders that preceded the addiction. These patients need psychiatric evaluation to determine a treatment plan for both problems. That may include an inpatient rehabilitation program.