I've been using XML-Sitemap since January 2007 but this issue came up with the newer versions.  The Change Log doesn't reference the new sitemap against the previous one.  URL's that are not new are listed as if they were just found.
Does it happen if you regenerate sitemap again?
I'm not sure how to regenerate a sitemap.  All I do is go to the "crawling tab" and hit Run.

6    2010-06-28 00:36    332    6.59s    6.04    0    0    0
7    2010-06-30 02:56    440    19.33s    7.10    110    2    2
8    2010-06-30 03:11    442    10.70s    7.10    110    0    0
9    2010-06-30 03:16    442    12.73s    7.10    110    0    0
10    2010-06-30 11:51    442    13.37s    7.10    110    0      0

The results would seem to indicate on the change log that I added 110 URL's on 2010-06-30 with 2 broken links.  The broken links were fixed and I ran it again for a total of 442 URL's.  Each subsequent run the change log indicated that I added 110 URL's which wasn't the case.

Thank you for your prompt reply.   I would appreciate any suggestions.

please let me know your generator URL/login in private message to check this.
I see that you were able to give it a try.  Any thoughts?  Seems like an intermittent problem.  It was working OK for a period of time and not it returned to its previous behavior. 
It reports 5 new pages when there has been no change and 9 new pages when 4 have been added:

No    Date/Time      Total pages           New URLs Removed URLs Broken links
32    2010-07-18 12:39    650    6.29s    9.42    5    0    0
33    2010-07-18 12:40    650    6.68s    9.46    5    0    0
34    2010-07-18 17:42    650    22.00s    9.46    5    0    0
35    2010-07-18 17:43    650    6.53s    9.46    5    0    0
36    2010-07-18 23:42    654    16.02s    9.45    9    0    0

try to remove all files from data/ folder and regenerate sitemap.
Thank you for your suggestion.  I deleted all the files off of the /data folder and ran Crawl again.  Interestingly, some of the configuration settings changed but not all. 
I ran Crawl about 5 times and it showed 633 pages each time.  All were listed as New URLs however no new URLs had been added.  So I have having the same problem as before.
I had configured XML-Sitemaps to generate sitemap.xml.gz  When I did so, sitemap.xml stopped updating.  After un-clicking the compression option, my total pages jumped to 647 and indicated that 14 were new.  This makes sense since there have been 14 new pages added since I last ran XML-Sitemaps without the compression option.  With the compression option disabled the last time, XML-Sitemaps was indicating that the new URL's were new every time I ran Crawl.  (as indicated in my last post)

Obviously I have an error somewhere.  Just not sure where.

Thank you for your prompt reply.

can you proviude a temporary ftp access via PM for troubleshooting?