i did think he was strange in Make Me A Perfect Murder. that episode is a favourite of mine but Falk seema a bit off and cold in this one. When he confronts Kay at the end of the episode he seems arrogant and distant and she hadn't been a killer he took a particular disliking to throughout the episode and yet at the end he just seems cold. That episode belongs to Trish Van Devere anyway, she was great.

I agree, Edward. If you notice it in season 7, then you'll REALLY notice it in the later seasons. For me it becomes an undeniable distraction in seasons 9 to 10. like a goofy grampa with an ego. The goof becomes even more obvious when the supporting cast is apparently told to act in an eye-rolling sort of demeanor toward the Lt. Which is a departure from what directors wanted to convey in the earlier years. Even as a senior detective, he was serious, direct and the smartest one in the room. It all changes at some point, as you mentioned.