I have never had it happen that a parent calls specifically to check on a child.
I have had parents call me during the day for other reasons i.e to tell me something about the schedule or the pickup time or that someone different would pick up that day but I have never had anyone call to check on their child.
I have had children who were dropped off with Tylenol and the warning that the child is not feeling 100% and still no call. I guess that parents figure that I would call if there were any issues.
I did used to call a few times when I had my own kids in daycare. I would call on the first day (for sure) to make sure how they are settling in and if there are any issues and I would call if they had been getting over an illness to see how they are.