Hi,
The date on the support site will normally just be the date the file was posted to the site and not the same as the bios build date since the bios will need to go through testing before it is released, so that sounds normal.
For bios files we're usually more worried about the bios version and installing the latest bios version, so don't normally pay much attention to the date as far as I know, but the same bios versions will have the same bios build dates.
