Push The Button

I entered the lift up to home, and this guy came in after me... I pushed button '12' for my floor and I waited for about a second... There can be a few possible scenarios that follow...

1. I ask him for his floor and I press him for it, then he says 'thank you'.

2. I take a step back, then he pushes the button on his own...

3. I ask him for his floor, and as he says it, he reaches out to push the button himself, then says 'thank you' to me...

Does scenario no. 3 sound the most familiar to you?? Yep, it happened today again... It seems to happen to me all the time, and at the same time, it's the most puzzling piece of human behaviour I have seen in a lift... yes, even weirder than peeing in the lift... at least the guy who pees may have a felt need that has to served...

The fact that when he enters the lift, he doesn't push the button, signals to me that he is waiting for me to ask him for the floor he would want to go to... So i asked him, and he told me 'six'... But then here comes the puzzling part, he then stretches his arm out to push the button on his own! This totally goes against why did he not push it himself right from the beginning when he entered...

So is it part of human behaviour that sometimes we just don't dare to ask for what we want? and we are too paisay or we are afraid of feeling bad?? but it's just pushing a button... so how paisay can he get? or are we brought up in an environment that tells us this is a 'humble' behaviour?? man, i'm confused...