Not in general. If the system loses confidence (bad lane markings, tight curve, that sort of thing) then it will ask (and then insist) that you put your hands on the wheel. But on a good road you can let go entirely and it will happily drive this way for a long time.

They are careful to state that you should always keep your hands on the wheel. There's even a little popup on the instrument panel that says this when you engage the system. But they don't enforce it.