Leaving the heated wing mirrors on

On my wife's golf when we bought it with 80k on the clock, on the journey home on the motorway the drivers side mirror glass came loose and was wobbling around all over the place all the way home.

My theory was that leaving the heated mirrors on too much had melted / had an effect on the glue that bonded the mirror glass onto the plastic holder.

Nothing that 20 mins and some super glue couldn't fix mind...