Sometimes people have a hard time making the distiction between bad behavior and submissive peeing. Forgetting their housetraining is one thing, but submissive peeing is something altogether differant and must be handled very carefully or it will get worse.
Normally, being a 6 year old dog, I would assume that never having been a submissive urinater before she couldn't be one now. However there has been a change recently right, someone stayed in the home, and after some time left?
Maybe the change triggered a submissive behavior the dog didn't normally have before? Does she pee only when you approach, or call her? Or does it seem to be something she goes off on her own and does by herself?