It was not luck whatsoever, and no the tabs were not broke or stressed in the least. A friend of mine owns a body shop for 37 years and only works on BMW, Porsche, Audi and he attends continuing education factory seminars for every new update and model change.
I've spent what equals to months at his shop over the years and he said there is more chance of damage popping off glass with breakage or mirror clip breakage as depressing the clips in the cover once exposed does not fully release the cover anyway so best to do it without touching glass mirrors. This was nowhere near my first mod and I never take chances.
I paid my way through college 40 years ago by installing custom stereo installations, so my knowledge and experience goes way back. If you ever tore apart a vehicle inside and out, there are many many panels that snap off that are made exactly the same way as the mirrors, some you use plastic pry tools to get it started some just your fingers, there is no difference. There are many videos on you tube showing my way, some good some not so good.