I leave him alone 5 - 7 hours a day. I leave him outside for up to an hour after I first wake up, plus the time i am at work (4 hours a day) and If I go shopping or to friends places.
I take him too the farmers market, my son's school, my parents house, dog park and a few other places, but I usually leave him home alot.
He is pretty good at going to the bathroom in "his spot" (the training pad in the back corner in the laundry) and goes outside. but with the kids i can't get up at crazy hours of the night, otherwise I would never get any sleep at all. today he had one accident, though. Hubby shut the laundry door so he couldn't get in there and he ran out to me and pee'd in front of me, cos i didn't understand what he wanted lol
If she has only done it once, it probably won't become a habit. Just make sure you take her too the toilet next time