At that age I would say it's perfectly normal, they really are sensitive to potential threats, as in the wild, they would have many. Your hand coming down into the tank can imitate prey coming from above (large birds). Baby corns are just 'wired' to be wary of things that could eat them.
What I've always done (unless I really needed to take the snake out of it's enclosure) is let it start to come out on it's own rather than reaching in and grabbing it. It can simply slide onto your hand this way. If you're nervous, this might be a good idea.. also helps with the trust issue (you're there and it's not so nervous of ya). Alternatively, especially if it doesn't want to come out.. approach it from a low angle and let your hand stay a certain distance away, keeping it still.. until you can see that the snake's defenses and/or signs of stress (watch the breathing..) have gone down and it knows better what you are
I'm not a big fan of uncovering them from their hides or picking up the hides with the occupant still inside as a way to get them out, but that does work as well. Ultimately you want it to get used to your hand coming into the tank to take it out, or to change water, etc. Shouldn't take long.. and they will usually outgrow a lot of the nervousness as they get bigger.