[thredds] over written file has old global attributes

I have a set of netcdf files that are being accessed via OpenDAP and are regularly overwritten. Most of the files, 29 sets of 31, update correctly but in 2 file sets the "Global Attributes" don't update to the new information although the "data" does. "ncdump -h" shows the correct information, :history = "MOST v2.080 11-05-2007 16:09:22" ; 
             :title = "Aleutian-Cascadia: Mwt 8.4, 21.00*b65" ;
in the headers but when I look at it in a browser, http://sift.pmel.noaa.gov/thredds/dodsC/data/crescent_runup_ha.nc.html 
I see the old file attributes,
history: "MOST v2.080 11-05-2007  11:49:33"
title: "Aleutian-Cascadia: Mwt 8.5, 29.00*b25".
If I restart tomcat then the correct information shows up.
I'm new at thredds so I may very well be doing something stupid but I could find no information. Below is the change I made to $tomcat_home/content/thredds/catalog.xml. Any suggestion? 
Thank you, Jean
<service name="ncdods" serviceType="OpenDAP" base="/thredds/dodsC/" />
  <datasetScan name="MOST tsunami model data" ID="mostDatasetScan"
       path="sims" location="/home/tg15/data/sims" serviceName="ncdods">
    <metadata inherited="true">
      <serviceName>ncdods</serviceName>
    </metadata>
    <filter>
      <include wildcard="*.nc"/>
    </filter>
    <sort>
      <lexigraphicByName increasing="true" />
    </sort>
  </datasetScan>
 ___________________________________________________________
  Jean Newman                             Tel: 206-526-6531
  NOAA Center for Tsunami Research
  NOAA/PMEL/OERD2 - UW/JISAO              FAX: 206-526-6485
  7600 Sand Point Way NE, Bldg. 3    jean.c.newman@xxxxxxxx
  Seattle, WA 98115-6349               jcn@xxxxxxxxxxxxxxxx
 _________________________. URL: http://nctr.pmel.noaa.gov/
                         (__________________________________