[He takes the napkin with a nod of thanks and cleans himself up. Being paranoid of what Connor has been touching is perfectly valid.]

When you said "magic", I was expecting something a little more... fantastical, I suppose. It still doesn't make sense, but you clearly have access to this source of energy.

[Basically, he believes her now. He analysed both the coffee and the juice and found they were both very different, and there's no way she could have tricked him.]