Dates separated with dashes instead of slashes are considered European date format by php. That means 09-01-1996 would be interpreted as January 9th. This explains why it is failing, but really our server code should account for it and allow it to pass.
I think the easiest solution is to use slash formatted dates like: 09/13/1996 instead of 09-13-1996 because that will solve the problem without needing to do any more. I can look into the issue with dashed dates in the meantime and try to get a fix out so that it will work properly in the future.