Something like this happened to me a few weeks ago. Did the vet give Rondo any kind of fluids before/after surgery?
I had quite a scare when I thought we were going to have to put our beloved kitty down. I had been taking him to the vet every day for a week - toward the end he started weeing himself in the car on the way to the vet, at the vet, and again in the car on the way home.
I assumed he was definitely going to die if he couldn't hold his urine like that, but the vet assured me that she'd been giving him so many fluids that he just couldn't hold it until he got home! So he was kind of "leaking" a little.
Now kitty's doing just fine! Once we stopped taking him for fluid IVs, he did his business in the box like normal!