She was a little exercised in her own mind as to this visitor.
As to this visitor, she was a little exercised in her own mind because she was uncertain as to who he was or where she knew him from. 
mnli hypothesis: As to this visitor, she was a little exercised in her own mind because she was uncertain as to who he was or where she knew him from.  premise: She was a little exercised in her own mind as to this visitor.