It's very likely he has a UTD (urinary tract disease). They may loose control but they can also be blocked- and that's life threatening.

He may have an inflammed baldder or urethra (like my Tigris, see thread below) or an urethral plug (Jenluckenbach's Rutherford, thread below) or crystals. All these things can have a bacterial infection in addition. In any case he has to see the vet. If he just starts with it I would not think it's behavioral.