I have always heard, from various sources, that your dog isn't "officially" potty trained until it asks to go out for potty time. Well, our first dog Sophie had spay incontinence and didn't always know when she needed to potty, but would try every time she went out, so we got into the habit of just putting her out every hour and a half to two hours. As we got Sirius and then Shelby this habit seems to have just continued, so at almost the age of two Shelby hasn't ever asked to go outside, but she also hasn't had an accident (aside from sick belly) inside since she was like 10 weeks old.
Well we are on vacation since Saturday in a condo, so we have had to do the potty on-leash thing (which by the way, she totally didn't understand at first) and so she isn't getting to go out as much as she would at home. Well this morning she asked to go outside by whining and getting up on the slider door! I guess this means that, at almost two years old, she is now "officially" potty trained!