I feel and think differently when talking to people?

I get the same thing. I think most people do. It's the whole "as soon as I see him I'm gonna give him a piece of my mind", and then they come through the door and you're all like "oh, hey". As far as I know it's normal behaviour. There's no way to fully understand the way the human brain works, so as long as it's not harming anyone, I'd just go with it.