Can i ask why you are bridging a openvpn interface ? why not route ?
For security reasons. My wireless access point has only WEP and so i have it connected to my second LAN Port on my home server. I then use openvpn to connect from from my notebook and bridge into the my local lan.
This setup separates the WiFi network completely from my lan and creates an additional security barrier for intruders.
Bernd