Gastrin level and/or Zollinger-Ellison Syndrome?

I have recently undergone surgery for acid reflux (Nissen fundoplication). I am still symptomatic. The doctor checked my serum gastrin level which was 122. They thought I may have an acid producing tumor because I had a significant acid level even though I was on Prevacid 30 mg twice a day. They say my gastrin level is normal but from what I read it is a little elevated. Does anyone know anything about it?

If I wasn't symptomactic I wouldn't be so concerned but I need to feel better and the doctors haven't come up with anything else.  Seems it should be repeated or further testing done if it is even a little elevated.... anyone with any suggestions????  Your input would be appreciated.