That’s not the point. The point is that the plugin registers the user’s e-mail address without asking permission or without warning.
You said “When using the Adwit banner manager you agree the terms as specified when you activate it.” in your e-mail, but you can’t do it witout notifying the user about that, and it wasn’t mentioned neither in the plugin nor at activation. So far the plugin leaks non-public information without warning.
The center tag is deprecated, and not part of the XHTML/HTML4 standard…