as far as I know dimples in the vinyl can have two reasons. Either the stamper was faulty, then all copies would have the very same dimple(s) at the very same spot. Or inferior quality vinyl was used. Then dimples may have resulted from dust or something like that in the hot vinyl.
As some of you have fine copies and others haven't I guess second reason is appropriate. On the other hand, if all faulty copies have dimples at the very same spot then there were two presses. One with a matrix from a fine stamper. One with a matrix from a faulty stamper.