Perhaps something else was also bothering you? I find when little things get on your nerves, it usually indicates that your tolerance level has been considerably shortened by other influences, and not always consciously. When someone is short-tempered with you without reason, it has significant impact upon your morale and whether you like it or not, there's a good chance you'll be unreasonable with someone else - the "bad vibes" being passed from one person to the next. The good news is the opposite can also be true...
So to get back to the subject - there's not a lot that annoys me typically. When the TV's too loud with bad reality shows perhaps...