why do i easily surprised/shocked over something that i foresaw, guessed, or predicted earlier?

i've asked this a long time ago before but got no answer. i'll try it again:

normally, or most people, would be shocked over something they don't know.

ex.: my wife was washing the dishes (while singing), then i surprised her from behind. she was shocked of course, because she didn't know i was coming at her. 

but in my case, if i were in my wife's position, i wouldn't be shocked at all, i don't know she was coming, but i feel nothing when she surprised me. instead, i would be shocked if i predicted or guessed beforehand that "someone is behind me now", and when my guess is right/happens, i'm really shocked, my heartbeat would rise for minutes.

another cases :

1. i was working in my house (office room), late at night. when an old grandpa clock stroke at midnight. i feel nothing, though before it stroke i didn't know it was just minutes before midnight because i was too focused on my work to look at the clock on my laptop, and the clock sound was pretty loud too.

2. i was watching tv alone while eating some snacks in the afternoon (my day off, and my wife was out to groceries). then somehow i feel that "something/someone is behind me", and when i turned my face to check it, i was really shocked that my "guess was right", although it's just my dog (no ghost story here).

it's just a few examples, but this happens all the time.