I recently had a contractor grindout old mortar on a late 1950's ranch home in Chicago. This work was done on common brick, not face brick. There are a few areas where very small bits of the new mortar seems to have fallen out. There are also a few very small 1/2-1 inch long hairline cracks in some of the new mortar joints. Should I be worried or is this somewhat normal? Overall, using my "untrained" eye the job does not look sloppy, and was done using a concave joint. thanks.