Well, at least it appears that way.
He could be scratching or readjusting or just letting his hand rest where it may. Or perhaps he was thinking about his beloved Big Penis Book, got an inappropriate, involuntary reaction, and had to hide something, just like when you were called up to the chalkboard in 8th grade algebra class.
Do kids still get called up to the chalkboard? Do they even know what chalk is? Oh, for simpler, chalk-and-erection-filled days.