Lord, have mercy!
I have this problem, too. Sometimes I react to a statement that I do not like, and my reaction becomes an angry one even if I did not intend it to be angry.
Indeed, like Fr. Chris once said (I don't remember, was it in our private conversation or on the OC.net forum), "when you suspect that your reaction will be angry, "sleep on it." Abstain from reacting until the next day. When I began to follow this rule, I noticed how greatly it helps me overcome my Irish temperament."