It’s not a short!! 
It’s static electricity, the bane of technicians and electronic assembly. You need more humidity or go barefoot.
I do encourage you to avoid touching sensitive electronics like that as they can cause dysfunction or damage. I have a DAC which I used as a preamp and whenever this happened the volume would shoot up to maximum. Ouch.
These shocks have very little current, but just enough voltage to damage sensitive electronics. One trick is to hold on to a key when you touch something that’s grounded (besides your gear). That will let you discharge the static your body has built up using a large surface area. Won’t lessen the discharge, just the pain of the zap.
In case you are curious, you can get a humidity monitor like this one. I like Govee because their phone apps are really solid. Put it next to your rack so you can see how dry your room is before you go adjusting something.