[It's a relief, but at the same time, John doesn't like him being alone with Sylar.]

Oh, thank God. I'm turning around now, but it'll be a few hours before I'm back. Is he just sort of staring at you? He does that.

[John raises his voice, uncertain how far away Sherlock is from Sylar.]

Sherlock, if you haven't eaten today, eat something. Or wash your hair. Just do something instead of standing there and staring. It creeps normal people out.

[Implying, of course, that Sylar is in any way, shape, or form normal.]