He doesn't like it. And Strange still doesn't grasp why Childermass seems to care about it so much. He could have stopped him! He almost stopped him in the first place, and yet that's somehow a bad thing?

Pity there's not that much self-awareness in all that arrogance. Strange lets Childermass grab his wrist and move it elsewhere, still glowering at the other man all the while.

"I don't think I need to remind you that you came over here and looked at my spying of your own free will." Yes, Strange was totally spying. But Childermass had the option of not looking and he didn't take it.