Upload to Broker Removes XP Driver Signing?

Bear with me on this since it's a bit lengthy. I looked for posts on
this subject but didn't find anything that seemed to fit.

While troubleshooting some issues from our Helpdesk related to driver
signing, I noticed that signed drivers that are uploaded to the broker
seem to lose their "signed" status during the process. This behavior can
be duplicated by obtaining a signed XP driver, uploading it to the
Broker through iManager, then manually retrieving the NDPSDRVR.ZIP file
created by the upload process and unzipping it. If you attempt to
manually add a local printer and select the unzipped ndps.inf file you
will see that Windows complains that the driver is not signed. And yet,
the original driver obtained from the manufacturer was signed.

This hasn't generally caused a problem since iPrint is installing the
printers, however we have seen situations recently with certain printers
and WinXP SP2 where users were being prompted regarding the unsigned
driver if they went into the properties of the printer. Not sure why
this would cause it to pop up, but it did.

I guess what I am curious to know is this:

Does the uploading of a signed WinXP driver to the Broker actually strip
the driver of its signed status? If so, why? If not, why does this
appear to be happening? Has anyone else seen this?

Thanks,

Anthony