Thanks for the picture e-man2!.
Is that plate stainless steel?.
Only thing that would concern me about this, would be wether there has ben some sort of sealing around the back of the GFCI plate to prevent moisture getting into the recept.
Or is this mirror equipped with one of those mirror demisters?.
One of the local FF's here is a glazier and he said he hates working with mirrors, you have to use special glue to hold them to the wall.
He also mentioned he has built up about 600 years of bad luck, if you are superstititously-inclined.
Shame on you Tony.