You may not experience it here as the contact form is slightly different, however from the contact page when a user sends a message the sent acknowledgement is just a little notification at the top of the page.
The send button disappears but reappears seconds later.
This is causing confusion amongst members who did not notice the notification or have left the computer after hitting send only to return to find the message is still in the box and the page has not changed.
As a result we receive duplicate requests and emails.
If at the very least could we have the entire page refresh on sending, the current system is too subtle for most users.