Yes I do get nervous at times. Some days, some flights I would just rather turn around and head home.
Unfortunately that hasn't always been an option, but on a couple of occasions I did walk away from flights cause of feelings I had. While nothing untoward ever happened to that flight, there were massive delays etc. down the line which meant I would have been stuck somewhere.
It is weird, I have flights to Asia for May and already I have the feeling I shouldn't be going.