My rockheaded female, Lily, has done this on three occasions. One: she had a bladder infection/stones that needed treating. Two: when her subtle "staring a hole through mommy over the gate to tell her I have to pee" tactic didn't work and she really had to go (she was standing on the couch to stare). Three: she was angry that I yelled at her over some misdeed and had swatted her tail with an envelope. Came back in the room and puddle on the couch. She still had the bladder infection at that time, so I give her a break on that one.
Long story short, I'd have her urine tested if she shows any other signs that it may be an infection. Symptoms include: frequent urination, lethargy (in a bulldog, I know!), taking longer than usual to go to the bathroom, straining to pee, foul smelling urine, cloudy urine, etc.
Sometimes, they're just rockheaded and pills don't fix that XD