Is she drinking a lot?
Been spayed recently....if so she may have spay incontenence which isn't all that uncommon and a course of pills should take care of it(not an infection just the bladder muscles get weak for some reason). She seems to know she has to go though and for the most part with incontenence they don't know they're "leaking", then again she could feel the need but doesn't have the control to hold it.
Could also be an infection.
Either way I think it's time to give the vet a call and see what they say, that way you can rule out if it's something medical.
If everything checks out ok maybe the vet has some ideas on what you can do, like controlling her water intake. I would only do it on the advice of your vet.
"An animal's eyes have the power to speak a great language." ~ Martin Buber
"All of the animals except for man know that the principle business of life is to enjoy it." ~ Samuel Butler
"The purity of a person's heart can be quickly measured by how they regard animals" ~ Anonymous