Wow, that sucks. I've seen this ALMOST happen, while walking out of the store. Someone flying up the row thinks it's an empty spot because they don't see the bike, start to turn in and slam on their brakes when they realize it's occupied. Luckily I've never had it hit. I always try to park the bike far back to make it most visible to those driving by.
Personally, I would call the lady and thank her for leaving a note, but not worry about the scratches. They add character.