This was also my experience. I followed the Aridus instructions to the letter and the forward most screw began backing out (thanks witness marks!). I cleaned and applied loctite blue and haven't had an issue since.
I also used loctite blue on these parts:
GG&G rail screws
GG&G stock adapter bolt
everything mounted to my GG&G rail
I've got 700+ shells on most of these added parts and nothing's shaked loose yet. The Streamlight Polytac light and the PA MD-20 red dot, both "budget" options, have also held up to the abuse.