Meg didn't find a reason to tell him to withdraw his hands, whether it be through words or by distancing herself from him, so he took that as a sign that his form of affection wasn't unwarranted. The gesture had been innocent, nothing more than simply stroking at her hair in that light manner, allowing his fingers to tangle in her hair just ever so slightly, but with Meg he was never sure of what to expect. It was confusing at times, but on the other hand, he was beginning to think that was to be expected with Meg. He was already behind, unable to tell just from specific cues what he was meant to be doing, because he was simply learning his way through all of this, so when there were conflicts between words and actions, he often just let them lie there. And then later attempted to get close again and see if he succeeded.
"Good," he said with a quick, simple nod. "Happy endings may not be typical, but they have to happen on occasion." After all, it couldn't just be in films alone that they were present. He'd never seen a musical before, so it would likely confuse him in that regard, why they were singing instead of simply speaking, because it would take less effort that way, but it was certain to create happier, joyful feelings as opposed to the tension and confusion that Casablanca brought on.
The movement of his hand in her hair resumed when she settled back in, almost like if he were petting a cat, but with greater care placed behind the motions.