I noticed some problems with posts, so I decided to investigate.

It seems that the third parameter when opening an XMLHttpRequest is a boolean value indicating whether things should be done in async mode or not. I missed that important bit of information when I wrote the core javascript that powers things. Without that parameter, the request defaulted to false - synchronous. So yes, my AJAX was SJAX. In other words, the form waited for everything to complete before disappearing. It seems almost Daily WTF worthy.