Here's mine:
-rwxr-xr-x@ 1 grettir admin 47 May 27 15:28 clearCookies.sh
-rwxr-xr-x@ 1 grettir staff 119 Nov 18 06:04 clearSafariCache.sh
-rwxr-xr-x@ 1 grettir admin 159 May 27 15:28 clearSafariHistory.sh
-rwxr-xr-x@ 1 grettir staff 89 Nov 18 06:04 clearSafariTPCache.sh
-rwxr-xr-x@ 1 grettir admin 193 Jul 20 02:17 clearSafariTPHistory.sh
The only obvious difference was that three of the scripts (although not the problematic one) were owned by the admin group. (Not sure why.) So I chowned the files to "grettir:staff" and, oddly enough, that appears to have resolved the problem. (Again, not sure why.)
I'll let you know if the problem reappears, but, otherwise, consider the issue resolved.
Thanks for your help.