According to Secunia PSI (Personal Software Inspector), version 3.1.9398.500 of soffice.exe, included with the current version 3-1 portable app, is not secure. They link to a secure version with a download file name of OOo_3.1.1_Win32Intel_install_wJRE_en-US.
If you aren't already doing it, I suggest installing copies of all your apps to a hard disk on a machine in your office, installing PSI, and setting it to "Enable Program Monitoring." You will then receive the earliest possible notification of security vulnerabilities, and can adjust your development schedule as needed to respond.
Thanks for the great product.