Sally learned to open most of the doors in our house within a few days of moving in. It was annoying but we didn't think much of it as they were the handle door knobs that the dog just has to pull down on and apply their weight correctly to open.
However, she has recently started to open our side door when she wants in--the side door has a ROUND door knob that you actually have to grip and turn. Now we are going to have to watch and make sure that this is the only round door knob in the house she can operate (and make sure the door is locked when she goes out so that she's not rewarded for her efforts), otherwise she is going to start letting herself into the basement again to raid the litter box....