It means that your machine is VERY repeatable. I think the story will be complete when you cut out your first parts. There are some machines that are very repeatable, but not very accurate (they will cut things a little off, but they will do the same thing each time). I think yours will turn out to be both accurate and repeatable ...
Just thinking out loud here: I think the acid test for a machine like this would be to run a fine grid pattern of lines with the spindle turned off and a scribe needle in the collet. Scribe onto a sheet metal plate with dykem blue on it for contrast. The moire pattern generated should tell you how accurate the machine is ... I might try this myself if I ever get my machine completed
