"And now that it's helped me once, I don't have to call on it ever again." Because Strange still doesn't like Creation. It's a stupid force of the universe that picked people to be Star Guardians for arbitrary methods, instead of picking people who can actually help and who actually knew what they were doing (he's not bitter about Wismuth, what made you think that).

"I am a little worried that when I get out of here, I'll have just turned entirely into a mirror. I'll need to come up with a way to heal myself should the situation call for it."

His reflection magic has been getting better...maybe he could physically manipulate the damn things himself and fix himself/his scars that way.