If people were to ask me if I have a fear....I might say I don't know.
But I do, and it's a silly one.
I'm always afraid I'll get electrocuted (metal knobs = amazing conductors) and that's the legacy of my old uni. We always play a game of chance, tapping the knob with the tip of our fingers before withdrawing quickly and hoping we don't get that painful jolt whenever we have to open doors. And I found I do that here too. I'm aware it's a psychological thing, the whole 'once bitten twice shy' saying. So if anyone noticed me tapping knobs before opening doors (though people won't) there you go, I have a perfect explanation.
Same with other things in life, we all had painful experiences, learn from them, and learn to avoid them.