1. Shorting a power supply should absolutely never be considered "Ok". Don't do it.
2. You should absolutely never change connections while powered.
Experience has shown me everyone ignores #2 until they finally blow up something they can't afford to replace.
And as a corollary to that, there was a thread recently suggesting always to load a sketch like bare minimum
each time you're done, so that next time you power up you don't have to scratch your head wondering what pins are doing what. My bare minimum
also puts pin 13 low- that LED is often on after a power up.