I would not have mind if the Knicks were to play them close, but the Wiz? In my opinion this should have been expected, because let downs happen all the time, especially during a back to back and you are playing against a poor team (look at the Knicks struggles against the Cavs tonight).
But a team with so much talent as the Heat, the point of emphasis should have been fighting against the letdown. They should have been challenge to play as if this was game 7 in the finals. No way they should have slept walk for over three quarters and think it is cool.
Bad habbits often have a way of creeping back later on (I've seen it happen to the Cavs in the past, and if the Heat don't watch out it can happen to them.)
The good news is the Heat have far better talent, and more time to straiten this out.