How to check if you've stopped following.

[Ughmahedhurtz]

[Addon] OhNoes: Screen Coloring/Alert addon. Updated![/url]

It flashes the whole screen red if you drop off follow.

Not quite what you asked for but thought it worth bringing to your attention

This. HIGHLY recommended. It's a very annoying screen flash, especially if you tweak it a bit. Makes it totally obvious when someone breaks follow. Also doesn't spam you silly with it every time you press the follow key again like that other mod did.