Hi,
when you configure the USB passthrough in the VM settings, you can enable the Stick for vMotion. If you didn't do this, you can't vMotion the VM.
It's not that bad though, as when you upgrade the host, the stick won't be reachable for the VM during the host reboot.
So remove the Stick now, plug it into the new 5.5 host, vMotion the VM to it and attach the USB to the VM again and this time enable it for vMotion.
Tim