Crepe Myrtle Sprouts

So I recently did a full reno on my landscaping which included cutting down some crepe myrtles that are located in areas that eventually became sodded yard. When I cut them down I immediately doused it in glyphosate as recommended and about a week or two later it was cut flush to the ground and the stump was grinded. I am starting to get some sprouts coming through the now mature st. aug in some of the areas where the crepe myrtles were. How can I address this issue besides just mowing over it everytime I do the yard?