Since I often make the mistake myself, I try not to correct people. With me, you can tell me the cat is MR MEOW and 5 minutes later I will call him SHE. it's Simply a dyslexic thing. If you say right I will instinctively turn left. I have even read words that are not in a sentence to make it mean the opposite. (EX/ if I read a written letter that said "He did want to go to the party" I might read it as "He did NOT want to go to the party") And not even notice until rereading.
So, I do it, and other people do it, and I try not to judge or correct them. It is not a personal insult and most likely totally unintentional.