It's hard to say if the root removal for that area of space would have had any detectable detriment to tree health, though our guess is it would be minimal, given that it's only a limited area within a much larger spread of roots for a tree that large. (Assuming there are no other significant space constraints, like being close to another building or other paved areas where the roots can't access moisture and nutrients.) You could always ask for the assessment of a certified arborist before removing any roots deliberately, but our educated guess is that root removal in that small of an area is nearly inconsequential given that the largest root was only an inch thick and was presumably not too close to the trunk (as we'd expect those roots to be much thicker). You can always help to reduce stress on a tree whose roots were injured by closely monitoring for watering needs, especially in our current drought conditions.

Miri