Alert emails periodically show "-0%" deals

[Klagmar]

I get emails like this every week or so. As far as I can tell, there actually is a deal when it sends these out, but for some reason the message does not include the storefront that has the deal. In this case, it's on sale from GreenManGaming, which I have marked as a valid store.

[dgw]

No one else seems to have taken note of this issue, but I see it often as well. Just now, even, there were several "-0%" deals mixed in with my most recent notification email.