"I'm offended, therefore you did something wrong"
The world is so filled with this. People, groups, families, countries go to war for this kind of nonsense.
Man, just drop it. If you got offended, well, I am pretty sure you are not going to die from it. Just walk away from the jerk. If this is possible for you, hell, just do it.
Life is beautiful enough, for you to forget these things.