Airflow is the name of this game. High-powered lights are built under the assumption that you're moving, and the airflow you create will cool them down. They will get warm, maybe even very warm, but I've never had any of my light systems over the last 20 years get too hot to hold. Were you moving for the time the light was on?
It is possible that the "Urban" series was designed with higher speeds (road, commuting) in mind, and thus uses less radiant cooling tech (fins). But that's just supposition on my part.
I was moving and it was cold out. However, I did dig up a VeloNews review of that series of lights and they mention the light gets hot. It might just be defective design.