same script, different permissions?

I have a script running in my cgi-bin which grabs information from e- mail message objects in a POP account and then creates and writes text files from the information. The script writes the articles to a sub- directory of the cgi-bin. The script is giving the files different sets of permissions, as follows... -rw-r----- 1 www www 1067 Sep 14 11:09 20000914160357.r -rw-r----- 1 www www 2316 Sep 14 11:09 20000914160359.r -rw-r----- 1 www www 854 Sep 14 11:10 20000914160448.r -rw-r----- 1 www www 803 Sep 14 11:10 20000914160449.r -rw-rw-r-- 1 www www 733 Sep 14 11:10 20000914160630.r -rw-r----- 1 www www 722 Sep 14 12:23 20000914171950.r -rw-rw-r-- 1 www www 737 Sep 14 12:45 20000914174152.r -rw-rw-r-- 1 www www 779 Sep 14 16:14 20000914210819.r -rw-r----- 1 www www 596 Sep 14 20:05 20000915005920.r any clue as to why that might be happening?