[Plugin: Fast Secure Contact Form] change field labels, error?

I have a website that has some 15 forms, each with about 50 fields. Everything works fine, but… I have noticed that on some forms the changing of field labels does not register. If I change some labels, save the changes by clicking the “update options” button I then see that my changes are gone. For now I have stopped editing the forms, because I am unsure about what goes on.

Is this a known bug? Will this be solved somewhere in the near future? Do you need more information?

http://wordpress.org/extend/plugins/si-contact-form/