Same thing happened to me when I tried the prototype. It's software not hardware problem. Ovi maps sucks on Maemo. Look at the video again at 4:28. Phone registers it after first touch and the selection activates before second touch. The slow response is due Ovi maps software not the screen.

What you are actually seeing is how slow, crappy and unresponsive the Ovi maps on Maemo is at the moment.