Hi Wendy,
Sorry for the (really) late reply to this. I was wondering if the filter=labels parameter is appearing because of a customization, so I searched through the custom components that are being used on that site and found a custom component that was rendering an anchor tag with the URL it links out to containing that parameter. It won't make a difference whether or not you have that since you are not passing the labels parameter (so specify what labels to filter by). You can remove it from the customization if you want to though. I will send you a private message with the name of the component.
-Doug
