Perhaps something weird is going on with your system with regards the cache directory the "executable" unpacks to. Without seeing your code all I can suggest is basic logical debugging actions. I'd use the verbose option when creating the package, then monitor the cached area to ensure that nothing is cleaning it up or removing any files for whatever reason.

You could specify an area outside of /tmp which would be imune from cetain sysadmin/housekeeping tasks. Look for -vvv and -T options witin the pp documentation.

chattr seems to have done the trick... all good for the past 4 weeks.