Unnatural cookie prompt?

[#1]

Not sure where to put this as it may be browser or router related.
I have noticed lately that I regularly get a cookie prompt "sb-ssl.google.com" in my Firefox browser, usually when I am simply in my router (techni"color" TG582n) web interface. Naturally I am puzzled as to why a google cookie is being offered to me when I'm doing that, not to mention at all. Any ideas?

[#2]

Are there any google related add-ons installed in Firefox?

[#3]

sb-ssl.google.com appears to be related to google safebrowsing. Firefox downloads updates to the list of malware and phishing sites from Google, Firefox tends to only do it when idle.

[#4]

RPM, no, not in the installation of FF that I get these prompts.
ejs, thanks. I guess it is that, then. Don't know why they want to set a cookie for it. As to the idle bit, though, I'm not idle. As I say, it's usually when I'm in the router interface, and typically when I have logged in and start 'browsing' it. Sometimes the cookie prompt does pop up when I'm in it but idling, however.