He threw 3 change ups in innings 1-3, according to pitchf/x which categorizes pitches by velocity/spin/movement. He threw 12 all game, 9 in innings 4-6. So, yes, he did mix it up more later on. My question is, how do we know that wasn't by design? You often hear about pitchers not giving hitters a look at everything the first time through the order, and bringing in more variety later in the game. That common pitching tactic is widely accepted and could easily explain why we saw the distribution we did, and, if the types of balls in play he allowed are fielded at the normal rate, he doesn't have a line that suggests this strategy won't work for him.
And, for all we know, the "body language" you were reading and subsequent mound visit could just as easily have been about recognizing that the strategy wasn't working due to the poor luck on groundballs, and McClure went out to tell him it was time to adjust the approach and check his mental state to make sure he wasn't freaking out over the results.
In the end, until someone comes out and says what was on their mind, we don't know what they were thinking. So let's stop trying to pretend that we do. Fair enough?