I can't comment on the fault needing new glass or not, because i don't have enough experience to know the various faults that can/do occur in relation to partial working etc etc, however i can post what i know from mine....
I do not have the memory option (although my nearside frame is for the full memory option setup) so please bear that in mind.
The interior mirror controls the dimming feature on the exterior mirror (note i said mirror singular, the pasenger side does not as standard carry the dimming/antiglare glass, you will see your drivers side carries a black beading around the glass - to have this option you must do it yourself and requires the frame with the wiring and relevant glass)
The mirror frames are electrically foldable, and this can be altered using STAR to have them opperate on locking/unlocking of the car - this has been known to cause problems with the wiring breaking, giving splurious warnings such as bulb out on the indicator, or other functions not working.
My bet would be on this wiring in the frame, if you are confident doing it, then i would remove the outer cover of the mirror, do while folded in, screw accessible then in the outer half if i remember correctly, then slide the cover off - i can't remember if you need to remove the mirror glass first, after this remove the door trim and unplug the mirror frame from the door module, then continuity check the wiring for breaks, repair/replace as necesary
EDIT:
also the interiror mirror has a green ish tint as it reacts, the door mirrors do not, they simply darken the image, and the interiror one reacts earlier/more than the door mirrors
