It is quite possible that Parks and Planning had to do a traffic impact study for the Department of Education. Such a study could be a part of the Master Plan for Montgomery County, which can be viewed at the Maryland-National Capital Parks and Planning commission on Georgia Avenue and Spring Street in Silver Spring. Their web site is found below. It is best in this important area of concern for you that you get the best information available. Their staff is informed, professional, and accomodating.
It is good that you are selling now. The problem, if there is one, will not affect you. Other actions you could take could enhance your home's value now.