Well, Strange is honestly a bit surprised to hear that! He blinks back a little bit of confusion before giving Peridot a slightly awkward smile.

"Thank you," he says, still not really bothering to hide the tone of surprise in his voice. There's a pause before he continues with, "I'm sorry I was a bit of an ass to you in Polaris. I haven't—" hmm, how best to explain this without it sounding like he considers his actions justified "—it's been hard lately. And I don't think I've coped all that well."