He sent her an 'I am offended you would suggest my hands are dirty' expression that was over the top and not rooted in any seriousness at all. He did as he was told, washing his hands thoroughly - he had some knowledge of triage and how to wash your hands to keep things sanitary, after all.

Alec re-approached her with his hands out, fingers spread. "Alright. See? Clean as a whistle."