It can be. My Dr. says sometimes that impatience is part of ADD. Anger in general can be a result of many things - it's part of what gets explored in therapy - not sure if it is a specific symptom though. Anger and impatience alone aren't enough to make a diagnosis - usually you have to have a number of symptoms for any given disorder. I'd bring it up though when you're in therapy or being evaluated - especially if it is an impairment for you in day to day functioning.