Four days ago, we had a patio slab poured. It was windy that day and lots of leaves were blown into the surface. The finishers were able to remove most of them. However, the wife noticed some small bits of leaves leaves on the surface and took a wire brush to them today (4 days after the pour). She said she did not exert tremendous pressure but lightly brushed the areas. Now those areas have turned white. QUESTION: Has she damaged the surface of the concrete causing those white spots to remain indefinitely or will those spots disappear? Note: We plan on staining the concrete once it is fully cured. Thank you.