How about this.......if her main concern is lunch then make up a monthly calendar, email it to her and stick to what is written on it. Then see if her questions cease. If she just moves on to start grilling you on a different round of questions daily about a new issue THEN you will know if it's trust or she was just curious about his day.

Personally, I worry MORE about parents who NEVER ask anything. I don't get a lot of mundane questioning because most of my daycare is transparent in that I post a monthly calendar so they already know the answer to things like food and special days etc. Most providers have calendars like this.