Levi has a sudden shiver, like his not-boyfriend is ruining his health unchecked. But, at the moment, Erwin is being inspected by protective mommy and that is the priority. When nosed, he straightens up promptly, not backing away, but not making any aggressive movements. See, he's super-skilled at both tree-hitting and potentially baby-protecting, but he's also a cool dude. All's good, mama.