Trigger discipline involves keeping the finger completely clear of the trigger guard until ready to fire

There is no correct resting position for your finger when not on the trigger. The primary consideration is that it is not on the trigger.

Even if she did have her finger on the trigger, this would only be bad if she had not checked that the gun was loaded, and was around others who did not know if the gun was loaded or not.

triple checked, visually confirmed

So check 4 times? 0_o

You need to check once. An empty chamber is unmistakable. Checking additional times may be a good habit to place the paranoid at ease, but its hardly a requirement. That is, until you've left it unattended, at which point it needs to be checked again.

You always have both hands on your firearm at any point of using the weapon unless it has been triple checked, visually confirmed, and safety on, with chamber open.

You claim you don't like that she's doing this, but you have absolutely no clue if she did check or not. Assuming she cleared the gun, then this is perfectly fine.

You don't go get your shotgun while curling your hair to make a "cool Facebook photo"

Hair rollers can stay in your hair for a significant amount of time, depending on the specific method you are using and how much curl you are going after. Up to an hour or more. This is not an active ongoing process that she interrupted just to grab a quick pic of her new shotgun. Its no different then putting a hat on and taking it off an hour later.