Hi Dave's Wife
Not knowing the history, I'm not sure what to think exactly. Of course, it would only be my opinion anyway.
The difference in the reading could be within a lab's margin of error. The lowest my lab reports is <.04 for all "undetectable" readings. I know some folks on the forum get results of <.01, but my lab doesn't provide that level of resolution.
Hopefully the surgeon will provide insight very soon. Don't be bashful about calling the doctor office and asking questions prior to your next appointment.