(on carpet, I wasn't thinking)

exactly...

Am I just freaking out for no reason?

yes, just be sure to ground yourself when doing your build.

My mouse is on a mouse pad, but with this new build, I kept getting shocked during the winter. I thought this was so weird, I googled and found others with the same thing. Logitech G500. I think the shock is from the mouse wheel.

When I get shocked, I hear something with my system sound "shutdown" like the default sounds of windows when you turn off your system.

I think this is just nuts me writing this. During winter, will be looking for a new winter mouse :) Keeping the G500 as my summer mouse. LOL

So your carpet is the issue for sure :)