I adopted Skip over 8 years ago (neutered, Male) and over the last 2 weeks he's begun urinating in one area of the house other than the litterbox (which is kept clean nearly daily).
I wasn't sure if it was Skip or his younger sister doing it, so I set up a video camera and within the 11 hr time frame, he urinated there once. He's never urinated there while I'm around, he usually uses the litterbox.
He's been checked for a UTI, and his kidneys are functioning normally.
Aside from the odd location of urination, he seems very relaxed...not stressed at all. He eats well, is of normal weight, drinks plenty of water through a fountain (the only water he will drink), no fleas, no bald spots, sleeps around 14 hrs a day, is very social, even with strangers. I take him outside almost daily. He has toys and a scratching pad, as well as a catwalk about 8 feet high.
What could be a possible cause for this odd behaviour?