Disregard the reroute node thing, I googled it. For anyone else who's had a long day at work and not enough coffee ¯\_(ツ)_/¯ - select it, and hit G to move it. I'd forgotten that functions like move, scale, and rotate can be used in the shader editor too - Woops!
Hi Harris, that is just a change in Blender...it still turns slightly greener, but less extreme than it used to be.
EDIT: I think it might not be greener, but just lighter...the idea being, that when you make Groups within Groups, each Level is getting a bit lighter...
I am not sure if there is another way for Left Click Selecters, but you can simply press G to move the selected Reroute point.
If you're using RCS, you can use the RMB to (Select and) drag it around...(you can also Select with LMB in the Node Editors).